diff --git a/docs/usage.md b/docs/usage.md
index 95b18715..fa029e2c 100644
--- a/docs/usage.md
+++ b/docs/usage.md
@@ -486,7 +486,7 @@ address of the tunnel peer. This is the IP address of the other CORE machine or
 physical machine, not an IP address of another virtual node.
 
 **NOTE:**
-   Be aware of possible MTU issues with GRE devices. The *gretap* device
+   Be aware of possible MTU (Maximum Transmission Unit) issues with GRE devices. The *gretap* device
    has an interface MTU of 1,458 bytes; when joined to a Linux bridge, the
    bridge's MTU
    becomes 1,458 bytes. The Linux bridge will not perform fragmentation for