--- a/latest/use-cases/index.html	Wed Jul 08 00:03:32 2015 -0400
+++ b/latest/use-cases/index.html	Wed Jul 08 00:06:32 2015 -0400
@@ -354,6 +354,11 @@
 An <a>entity</a> that provides a source of funds as required by a
 <a>transaction</a>.
       </dd>
+      <dt><dfn>transaction</dfn></dt>
+      <dd>
+An economic exchange between a <a>payer</a> and one or more 
+<a title="payee">payees</a>.
+      </dd>
       <dt><dfn>payment instrument</dfn></dt>
       <dd>
 A mechanism used to transfer value from a <a>payer</a> to a