diff --git a/CPP20.md b/CPP20.md
index 97cc9a2..032ae80 100644
--- a/CPP20.md
+++ b/CPP20.md
@@ -19,6 +19,7 @@ C++20 includes the following new language features:
 
 C++20 includes the following new library features:
 - [concepts library](#concepts-library)
+- [synchronized buffered outputstream](#synchronized-buffered-outputstream)
 
 ## C++20 Language Features
 
@@ -364,6 +365,12 @@ Concepts are also provided by the standard library for building more complicated
 
 See also: [concepts](#concepts).
 
+### synchronized buffered outputstream
+Buffers output operations for the wrapped output stream ensuring synchronization (i.e. no interleaving of output).
+```c++
+std::osyncstream{std::cout} << "The value of x is:" << x << std::endl;
+```
+
 ## Acknowledgements
 * [cppreference](http://en.cppreference.com/w/cpp) - especially useful for finding examples and documentation of new library features.
 * [C++ Rvalue References Explained](http://thbecker.net/articles/rvalue_references/section_01.html) - a great introduction I used to understand rvalue references, perfect forwarding, and move semantics.
diff --git a/README.md b/README.md
index 10f8a83..2134639 100644
--- a/README.md
+++ b/README.md
@@ -19,6 +19,7 @@ C++20 includes the following new language features:
 
 C++20 includes the following new library features:
 - [concepts library](#concepts-library)
+- [synchronized buffered outputstream](#synchronized-buffered-outputstream)
 
 C++17 includes the following new language features:
 - [template argument deduction for class templates](#template-argument-deduction-for-class-templates)
@@ -456,6 +457,12 @@ Concepts are also provided by the standard library for building more complicated
 
 See also: [concepts](#concepts).
 
+### synchronized buffered outputstream
+Buffers output operations for the wrapped output stream ensuring synchronization (i.e. no interleaving of output).
+```c++
+std::osyncstream{std::cout} << "The value of x is:" << x << std::endl;
+```
+
 ## C++17 Language Features
 
 ### Template argument deduction for class templates