diff --git a/.rubocop.yml b/.rubocop.yml
index 43ccb9f56..e6a1a7e47 100644
--- a/.rubocop.yml
+++ b/.rubocop.yml
@@ -10,7 +10,7 @@ AllCops:
 
 Style/IndentationConsistency:
   Exclude:
-    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/attributes.rb
     - lib/active_model/serializer/adapter/fragment_cache.rb
     - lib/active_model/serializer/adapter/json.rb
     - lib/active_model/serializer/adapter/json/fragment_cache.rb
@@ -21,7 +21,7 @@ Style/IndentationConsistency:
 
 Style/IndentationWidth:
   Exclude:
-    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/attributes.rb
     - lib/active_model/serializer/adapter/fragment_cache.rb
     - lib/active_model/serializer/adapter/json.rb
     - lib/active_model/serializer/adapter/json/fragment_cache.rb
@@ -32,7 +32,7 @@ Style/IndentationWidth:
 
 Style/AccessModifierIndentation:
   Exclude:
-    - lib/active_model/serializer/adapter/flatten_json.rb
+    - lib/active_model/serializer/adapter/attributes.rb
     - lib/active_model/serializer/adapter/fragment_cache.rb
     - lib/active_model/serializer/adapter/json.rb
     - lib/active_model/serializer/adapter/json/fragment_cache.rb
diff --git a/README.md b/README.md
index 3e17220e3..42f6cd7a4 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ AMS does this through two components: **serializers** and **adapters**.
 Serializers describe _which_ attributes and relationships should be serialized.
 Adapters describe _how_ attributes and relationships should be serialized.
 
-By default AMS will use the **Flatten Json Adapter**. But we strongly advise you to use **JsonApi Adapter** that follows 1.0 of the format specified in [jsonapi.org/format](http://jsonapi.org/format).
+By default AMS will use the **Attributes Adapter**. But we strongly advise you to use **JsonApi Adapter** that follows 1.0 of the format specified in [jsonapi.org/format](http://jsonapi.org/format).
 Check how to change the adapter in the sections bellow.
 
 # RELEASE CANDIDATE, PLEASE READ
@@ -66,7 +66,7 @@ ActiveModel::Serializer.config.adapter = :json_api
 You won't need to implement an adapter unless you wish to use a new format or
 media type with AMS.
 
-If you want to have a root key on your responses you should use the Json adapter, instead of the default FlattenJson:
+If you want to have a root key on your responses you should use the Json adapter, instead of the default Attributes:
 
 ```ruby
 ActiveModel::Serializer.config.adapter = :json
@@ -137,7 +137,7 @@ render json: @post, meta: { total: 10 }, meta_key: "custom_meta"
 ```
 
 `meta` will only be included in your response if you are using an Adapter that supports `root`,
-as JsonAPI and Json adapters, the default adapter (FlattenJson) doesn't have `root`.
+as JsonAPI and Json adapters, the default adapter (Attributes) doesn't have `root`.
 
 ### Using a serializer without `render`
 
@@ -190,7 +190,7 @@ end
 
 ### Built in Adapters
 
-#### FlattenJSON
+#### Attributes
 
 It's the default adapter, it generates a json response without a root key.
 Doesn't follow any specifc convention.
diff --git a/docs/general/adapters.md b/docs/general/adapters.md
index 59d4cbae3..bbc6dfa66 100644
--- a/docs/general/adapters.md
+++ b/docs/general/adapters.md
@@ -3,11 +3,11 @@
 AMS does this through two components: **serializers** and **adapters**.
 Serializers describe _which_ attributes and relationships should be serialized.
 Adapters describe _how_ attributes and relationships should be serialized.
-You can use one of the built-in adapters (```FlattenJSON``` is the default one) or create one by yourself, but you won't need to implement an adapter unless you wish to use a new format or media type with AMS.
+You can use one of the built-in adapters (```Attributes``` is the default one) or create one by yourself, but you won't need to implement an adapter unless you wish to use a new format or media type with AMS.
 
 ## Built in Adapters
 
-### FlattenJSON - Default
+### Attributes - Default
 
 It's the default adapter, it generates a json response without a root key.
 Doesn't follow any specifc convention.
@@ -51,7 +51,7 @@ ActiveModel::Serializer.config.adapter = :json_api
 ```
 
 If you want to have a root key for each resource in your responses, you should use the Json or
-JsonApi adapters instead of the default FlattenJson:
+JsonApi adapters instead of the default Attributes:
 
 ```ruby
 ActiveModel::Serializer.config.adapter = :json
diff --git a/docs/general/configuration_options.md b/docs/general/configuration_options.md
index 2512bf469..8288b3c09 100644
--- a/docs/general/configuration_options.md
+++ b/docs/general/configuration_options.md
@@ -4,7 +4,7 @@ The following configuration options can be set on `ActiveModel::Serializer.confi
 
 ## General
 
-- `adapter`: The [adapter](adapters.md) to use. Possible values: `:flatten_json, :json, :json_api`. Default: `:flatten_json`.
+- `adapter`: The [adapter](adapters.md) to use. Possible values: `:attributes, :json, :json_api`. Default: `:attributes`.
 
 ## JSON API
 
diff --git a/docs/howto/add_pagination_links.md b/docs/howto/add_pagination_links.md
index d9f01e49c..11ce9b9c5 100644
--- a/docs/howto/add_pagination_links.md
+++ b/docs/howto/add_pagination_links.md
@@ -110,6 +110,6 @@ ex.
 }
 ```
 
-### FlattenJSON adapter
+### Attributes adapter
 
 This adapter does not allow us to use `meta` key, due to that it is not possible to add pagination links.
diff --git a/docs/howto/add_root_key.md b/docs/howto/add_root_key.md
index f03388033..51f0f1e1f 100644
--- a/docs/howto/add_root_key.md
+++ b/docs/howto/add_root_key.md
@@ -1,6 +1,6 @@
 # How to add root key
 
-Add the root key to your API is quite simple with AMS. The **Adapter** is what determines the format of your JSON response. The default adapter is the ```FlattenJSON``` which doesn't have the root key, so your response is something similar to:
+Add the root key to your API is quite simple with AMS. The **Adapter** is what determines the format of your JSON response. The default adapter is the ```Attributes``` which doesn't have the root key, so your response is something similar to:
 
 ```json
 {
diff --git a/lib/active_model/serializer/adapter.rb b/lib/active_model/serializer/adapter.rb
index f7ab6e985..4ef0d24d0 100644
--- a/lib/active_model/serializer/adapter.rb
+++ b/lib/active_model/serializer/adapter.rb
@@ -5,11 +5,11 @@ class Adapter
       ADAPTER_MAP = {}
       private_constant :ADAPTER_MAP if defined?(private_constant)
       extend ActiveSupport::Autoload
+      autoload :Attributes
+      autoload :Null
       autoload :FragmentCache
       autoload :Json
       autoload :JsonApi
-      autoload :Null
-      autoload :FlattenJson
       autoload :CachedSerializer
 
       def self.create(resource, options = {})
@@ -74,7 +74,8 @@ def lookup(adapter)
         # @api private
         def find_by_name(adapter_name)
           adapter_name = adapter_name.to_s.classify.tr('API', 'Api')
-          ActiveModel::Serializer::Adapter.const_get(adapter_name.to_sym) or # rubocop:disable Style/AndOr
+          "ActiveModel::Serializer::Adapter::#{adapter_name}".safe_constantize ||
+            "ActiveModel::Serializer::Adapter::#{adapter_name.pluralize}".safe_constantize or # rubocop:disable Style/AndOr
             fail UnknownAdapterError
         end
         private :find_by_name
diff --git a/lib/active_model/serializer/adapter/flatten_json.rb b/lib/active_model/serializer/adapter/attributes.rb
similarity index 83%
rename from lib/active_model/serializer/adapter/flatten_json.rb
rename to lib/active_model/serializer/adapter/attributes.rb
index 429818dca..40cf9a316 100644
--- a/lib/active_model/serializer/adapter/flatten_json.rb
+++ b/lib/active_model/serializer/adapter/attributes.rb
@@ -1,8 +1,8 @@
-class ActiveModel::Serializer::Adapter::FlattenJson < ActiveModel::Serializer::Adapter::Json
+class ActiveModel::Serializer::Adapter::Attributes < ActiveModel::Serializer::Adapter
         def serializable_hash(options = nil)
           options ||= {}
           if serializer.respond_to?(:each)
-            result = serializer.map { |s| FlattenJson.new(s).serializable_hash(options) }
+            result = serializer.map { |s| Attributes.new(s).serializable_hash(options) }
           else
             hash = {}
 
@@ -43,7 +43,7 @@ def fragment_cache(cached_hash, non_cached_hash)
 
         private
 
-        # no-op: FlattenJson adapter does not include meta data, because it does not support root.
+        # no-op: Attributes adapter does not include meta data, because it does not support root.
         def include_meta(json)
           json
         end
diff --git a/lib/active_model/serializer/adapter/json.rb b/lib/active_model/serializer/adapter/json.rb
index b24719366..9b9b9cdce 100644
--- a/lib/active_model/serializer/adapter/json.rb
+++ b/lib/active_model/serializer/adapter/json.rb
@@ -4,7 +4,7 @@ class ActiveModel::Serializer::Adapter::Json < ActiveModel::Serializer::Adapter
 
         def serializable_hash(options = nil)
           options ||= {}
-          { root => FlattenJson.new(serializer).serializable_hash(options) }
+          { root => Attributes.new(serializer).serializable_hash(options) }
         end
 
         private
diff --git a/lib/active_model/serializer/configuration.rb b/lib/active_model/serializer/configuration.rb
index 102c821e1..19b2df1ea 100644
--- a/lib/active_model/serializer/configuration.rb
+++ b/lib/active_model/serializer/configuration.rb
@@ -6,7 +6,7 @@ module Configuration
 
       included do |base|
         base.config.array_serializer = ActiveModel::Serializer::ArraySerializer
-        base.config.adapter = :flatten_json
+        base.config.adapter = :attributes
         base.config.jsonapi_resource_type = :plural
       end
     end
diff --git a/test/adapter_test.rb b/test/adapter_test.rb
index 75efac15d..8296fb342 100644
--- a/test/adapter_test.rb
+++ b/test/adapter_test.rb
@@ -21,7 +21,7 @@ def test_serializer
 
       def test_create_adapter
         adapter = ActiveModel::Serializer::Adapter.create(@serializer)
-        assert_equal ActiveModel::Serializer::Adapter::FlattenJson, adapter.class
+        assert_equal ActiveModel::Serializer::Adapter::Attributes, adapter.class
       end
 
       def test_create_adapter_with_override
diff --git a/test/serializers/adapter_for_test.rb b/test/serializers/adapter_for_test.rb
index ae7c95bb8..17517dd46 100644
--- a/test/serializers/adapter_for_test.rb
+++ b/test/serializers/adapter_for_test.rb
@@ -7,7 +7,7 @@ def setup
         @previous_adapter = ActiveModel::Serializer.config.adapter
         # Eager load adapters
         ActiveModel::Serializer::Adapter.eager_load!
-        [:json_api, :flatten_json, :null, :json].each do |adapter_name|
+        [:json_api, :attributes, :null, :json].each do |adapter_name|
           ActiveModel::Serializer::Adapter.lookup(adapter_name)
         end
       end
@@ -18,7 +18,7 @@ def teardown
 
       def test_returns_default_adapter
         adapter = ActiveModel::Serializer.adapter
-        assert_equal ActiveModel::Serializer::Adapter::FlattenJson, adapter
+        assert_equal ActiveModel::Serializer::Adapter::Attributes, adapter
       end
 
       def test_overwrite_adapter_with_symbol
@@ -68,15 +68,15 @@ def test_adapter_map
         expected_adapter_map = {
           'json'.freeze              => ActiveModel::Serializer::Adapter::Json,
           'json_api'.freeze          => ActiveModel::Serializer::Adapter::JsonApi,
-          'flatten_json'.freeze      => ActiveModel::Serializer::Adapter::FlattenJson,
-          'null'.freeze              => ActiveModel::Serializer::Adapter::Null
+          'attributes'.freeze => ActiveModel::Serializer::Adapter::Attributes,
+          'null'.freeze => ActiveModel::Serializer::Adapter::Null
         }
         assert_equal ActiveModel::Serializer::Adapter.adapter_map, expected_adapter_map
       end
 
       def test_adapters
         assert_equal ActiveModel::Serializer::Adapter.adapters.sort, [
-          'flatten_json'.freeze,
+          'attributes'.freeze,
           'json'.freeze,
           'json_api'.freeze,
           'null'.freeze
@@ -114,8 +114,8 @@ def test_lookup_adapter_for_unknown_name
       end
 
       def test_adapter
-        assert_equal ActiveModel::Serializer.config.adapter, :flatten_json
-        assert_equal ActiveModel::Serializer.adapter, ActiveModel::Serializer::Adapter::FlattenJson
+        assert_equal ActiveModel::Serializer.config.adapter, :attributes
+        assert_equal ActiveModel::Serializer.adapter, ActiveModel::Serializer::Adapter::Attributes
       end
 
       def test_register_adapter
diff --git a/test/serializers/attribute_test.rb b/test/serializers/attribute_test.rb
index c0b2e30bb..5ca7f8428 100644
--- a/test/serializers/attribute_test.rb
+++ b/test/serializers/attribute_test.rb
@@ -21,7 +21,7 @@ def test_json_serializable_hash
       def test_attribute_inheritance_with_key
         inherited_klass = Class.new(AlternateBlogSerializer)
         blog_serializer = inherited_klass.new(@blog)
-        adapter = ActiveModel::Serializer::Adapter::FlattenJson.new(blog_serializer)
+        adapter = ActiveModel::Serializer::Adapter::Attributes.new(blog_serializer)
         assert_equal({ :id => 1, :title => 'AMS Hints' }, adapter.serializable_hash)
       end
 
diff --git a/test/serializers/configuration_test.rb b/test/serializers/configuration_test.rb
index e623cde97..24e02836d 100644
--- a/test/serializers/configuration_test.rb
+++ b/test/serializers/configuration_test.rb
@@ -8,7 +8,7 @@ def test_array_serializer
       end
 
       def test_default_adapter
-        assert_equal :flatten_json, ActiveModel::Serializer.config.adapter
+        assert_equal :attributes, ActiveModel::Serializer.config.adapter
       end
     end
   end
diff --git a/test/serializers/meta_test.rb b/test/serializers/meta_test.rb
index 976dc52f0..7c893a590 100644
--- a/test/serializers/meta_test.rb
+++ b/test/serializers/meta_test.rb
@@ -27,7 +27,7 @@ def test_meta_is_present_with_root
       end
 
       def test_meta_is_not_included_when_root_is_missing
-        # load_adapter uses FlattenJson Adapter
+        # load_adapter uses Attributes Adapter
         adapter = load_adapter(meta: { total: 10 })
         expected = {
           id: 1,
@@ -67,8 +67,8 @@ def test_meta_key_is_used_with_json_api
 
       def test_meta_is_not_present_on_arrays_without_root
         serializer = ArraySerializer.new([@blog], meta: { total: 10 })
-        # FlattenJSON doesn't have support to root
-        adapter = ActiveModel::Serializer::Adapter::FlattenJson.new(serializer)
+        # Attributes doesn't have support to root
+        adapter = ActiveModel::Serializer::Adapter::Attributes.new(serializer)
         expected = [{
           id: 1,
           name: 'AMS Hints',
@@ -113,7 +113,7 @@ def test_meta_is_present_on_arrays_with_root
       private
 
       def load_adapter(options)
-        options = options.merge(adapter: :flatten_json, serializer: AlternateBlogSerializer)
+        options = options.merge(adapter: :attributes, serializer: AlternateBlogSerializer)
         ActiveModel::SerializableResource.new(@blog, options)
       end
     end