diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 4c4927ab4e..59d7c0acbc 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -374,6 +374,28 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-BASE_LIB'><glossterm>BASE_LIB</glossterm>
+            <glossdef>
+                <para>
+                    The library directory name for the CPU or Application
+                    Binary Interface (ABI) tune.
+                    The <filename>BASE_LIB</filename> applies only in the
+                    Multilib context.
+                    See the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#combining-multiple-versions-library-files-into-one-image'>Combining Multiple Versions of Library Files into One Image</ulink>"
+                    section in the Yocto Project Development Manual for
+                    information on Multilib.
+                </para>
+
+                <para>
+                    The <filename>BASE_LIB</filename> variable is defined in
+                    the machine include files in the
+                    <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>Source Directory</ulink>.
+                    If Multilib is not being used, the value defaults to "lib".
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-BB_DANGLINGAPPENDS_WARNONLY'><glossterm>BB_DANGLINGAPPENDS_WARNONLY</glossterm>
             <glossdef>
                 <para>