diff --git a/handleMessage.js b/handleMessage.js
index e273361..07f72db 100644
--- a/handleMessage.js
+++ b/handleMessage.js
@@ -1,22 +1,33 @@
 'use strict';
 
-const wordnet = require('wordnet');
-
+// `wordnet` is a server-only package (it reads the WordNet database off disk).
+// It MUST NOT be required at module top level: Etherpad's client bundler pulls
+// plugin hook modules into the browser bundle, and evaluating wordnet's module
+// body in the browser silently hangs the editor bootstrap — the ace_outer
+// iframe is never created and no error is thrown, so every pad (and the whole
+// frontend test suite) times out. Requiring it lazily inside the hook keeps the
+// module body from ever running client-side while still working on the server.
+let wordnet = null;
 let initPromise = null;
 const ensureInit = () => {
+  if (!wordnet) wordnet = require('wordnet');
   if (!initPromise) initPromise = wordnet.init();
   return initPromise;
 };
 
 const sendDefinition = (context, definitions) => {
-  context.client.json.send({
+  // `context.client.json.send(...)` was the socket.io v2 API and no longer
+  // exists, so the reply never reached the client (the gritter never showed).
+  // Emit over the modern socket, and trust the server-resolved author/pad from
+  // sessionInfo rather than client-supplied ids.
+  context.socket.emit('message', {
     type: 'COLLABROOM',
     data: {
       type: 'CUSTOM',
       payload: {
         action: 'recieveDefineMessage',
-        authorId: context.message.data.message.myAuthorId,
-        padId: context.message.data.message.padId,
+        authorId: context.sessionInfo.authorId,
+        padId: context.sessionInfo.padId,
         message: definitions,
       },
     },
@@ -26,7 +37,10 @@ const sendDefinition = (context, definitions) => {
 exports.handleMessage = async (hookName, context) => {
   if (!(context && context.message && context.message.data &&
         context.message.data.type && context.message.data.action === 'sendDefineMessage')) {
-    return [null];
+    // Not our message — return nothing so the message keeps flowing. Returning
+    // `[null]` here would tell core to DROP every non-define message (typing,
+    // cursor moves, …), silently breaking the pad.
+    return;
   }
   try {
     await ensureInit();