diff --git a/adapter/README.md b/adapter/README.md
index c9a97b6c3..6453a2ce7 100644
--- a/adapter/README.md
+++ b/adapter/README.md
@@ -102,7 +102,7 @@ Use the Adapter pattern when
 
 * You want to use an existing class, and its interface does not match the one you need
 * You want to create a reusable class that cooperates with unrelated or unforeseen classes, that is, classes that don't necessarily have compatible interfaces
-* You need to use several existing subclasses, but it's impractical to adapt their interface by subclassing every one. An object adapter can adapt the interface of its parent class.
+* You need to use several existing subclasses, but it's impractical to adapt their interface by subclassing everyone. An object adapter can adapt the interface of its parent class.
 * Most of the applications using third-party libraries use adapters as a middle layer between the application and the 3rd party library to decouple the application from the library. If another library has to be used only an adapter for the new library is required without having to change the application code.
 
 ## Consequences: