diff --git a/templates/zephyr/compose.html b/templates/zephyr/compose.html
index 91aadf486e..bb08cfa64c 100644
--- a/templates/zephyr/compose.html
+++ b/templates/zephyr/compose.html
@@ -43,7 +43,7 @@
                   <i class="icon-vector-narrow icon-vector-small"></i>
                   <input type="text" class="recipient_box" name="subject" id="subject"
                          maxlength="60"
-                         value="" placeholder="Subject" autocomplete="off" tabindex="130"/>
+                         value="" placeholder="Topic" autocomplete="off" tabindex="130"/>
               </td>
             </tr>
             <tr id="private-message">
diff --git a/templates/zephyr/keyboard_shortcuts.html b/templates/zephyr/keyboard_shortcuts.html
index 2d462d0e46..a946d1b282 100644
--- a/templates/zephyr/keyboard_shortcuts.html
+++ b/templates/zephyr/keyboard_shortcuts.html
@@ -81,7 +81,7 @@
       </tr>
       <tr>
         <td class="hotkey">S</td>
-        <td class="definition">Narrow by subject</td>
+        <td class="definition">Narrow by topic</td>
         </tr>
       <tr>
         <td class="hotkey">v</td>
diff --git a/templates/zephyr/new-user.html b/templates/zephyr/new-user.html
index 37341895d7..0b7f20ebec 100644
--- a/templates/zephyr/new-user.html
+++ b/templates/zephyr/new-user.html
@@ -16,9 +16,9 @@
       Here's what you need to know:</p>
 
     <ul>
-      <li>Every message has a <b>stream</b> and a <b>subject</b></li>
+      <li>Every message has a <b>stream</b> and a <b>topic</b></li>
       <li>A stream is kind of like a mailing list -- it represents a group of people -- and anyone can <i>subscribe</i> to a stream and start getting traffic there</li>
-      <li>A subject, on the other hand, is what the message is <i>actually about</i></li>
+      <li>A topic, on the other hand, is what the message is <i>actually about</i></li>
       <li>(You can, of course, send private messages.)</li>
       <li>All of these are displayed simultaneously, in an interleaved way, chronologically</li>
       <li>Time flows down</li>
@@ -35,14 +35,14 @@
 
     <p>Here, we have three conversations occurring simultaneously:</p>
     <ul>
-      <li>One on stream "zulip" with subject "Lunch", about where to go to lunch</li>
-      <li>One on stream "zulip" with subject "Zulip testers", about early beta testers</li>
+      <li>One on stream "zulip" with topic "Lunch", about where to go to lunch</li>
+      <li>One on stream "zulip" with topic "Zulip testers", about early beta testers</li>
       <li>One automated notification on stream "commits", about a commit made to the repository</li>
     </ul>
 
     <h3>Some things to know</h3>
     <ul>
-      <li>"Enter" will start a reply to the message with the blue line by it (in the example above, the one with subject "Zulip testers")</li>
+      <li>"Enter" will start a reply to the message with the blue line by it (in the example above, the one with topic "Zulip testers")</li>
       <li>When you send the reply, it will appear at the very bottom of the stream (not directly below the message you reply to)</li>
       <li>We have mobile apps, an API, and integrations with many popular services</li>
     </ul>
diff --git a/templates/zephyr/tutorial_finale.html b/templates/zephyr/tutorial_finale.html
index cced2b3a54..f8af042df6 100644
--- a/templates/zephyr/tutorial_finale.html
+++ b/templates/zephyr/tutorial_finale.html
@@ -7,7 +7,7 @@
     <b>We make it easy for you to see the things you care about.</b>
 
     <p>
-      Streams, subjects, and narrowing let you zoom in on the things that
+      Streams, topics, and narrowing let you zoom in on the things that
       interest you, and quickly ignore the ones that don't.
     </p>
     <p>
diff --git a/zephyr/lib/actions.py b/zephyr/lib/actions.py
index 46c605fc53..4317985ed2 100644
--- a/zephyr/lib/actions.py
+++ b/zephyr/lib/actions.py
@@ -403,12 +403,12 @@ def check_message(sender, client, message_type_name, message_to,
             return "Invalid stream name"
 
         if subject_name is None:
-            return "Missing subject"
+            return "Missing topic"
         subject = subject_name.strip()
         if subject == "":
-            return "Subject can't be empty"
+            return "Topic can't be empty"
         if len(subject) > MAX_SUBJECT_LENGTH:
-            return "Subject too long"
+            return "Topic too long"
         ## FIXME: Commented out temporarily while we figure out what we want
         # if not valid_stream_name(subject):
         #     return json_error("Invalid subject name")
@@ -992,10 +992,10 @@ def do_update_message(user_profile, message_id, subject, content):
     if subject is not None:
         subject = subject.strip()
         if subject == "":
-            raise JsonableError("Subject can't be empty")
+            raise JsonableError("Topic can't be empty")
 
         if len(subject) > MAX_SUBJECT_LENGTH:
-            raise JsonableError("Subject too long")
+            raise JsonableError("Topic too long")
         event["orig_subject"] = message.subject
         message.subject = subject
         event["subject"] = subject
diff --git a/zephyr/static/js/tutorial.js b/zephyr/static/js/tutorial.js
index 5aacf023fd..56f1c0b051 100644
--- a/zephyr/static/js/tutorial.js
+++ b/zephyr/static/js/tutorial.js
@@ -317,7 +317,7 @@ function subject() {
     var spotlight_message = rows.first_visible();
     var bar = spotlight_message.prev(".recipient_row");
     var placement = maybe_tweak_placement("bottom");
-    create_and_show_popover(bar, placement, "Subjects", "tutorial_subject");
+    create_and_show_popover(bar, placement, "Topics", "tutorial_subject");
 
     var my_popover = $("#tutorial-subject").closest(".popover");
     if (placement === "bottom") { // Wider screen, popover is on bottom.
diff --git a/zephyr/static/templates/actions_popover_content.handlebars b/zephyr/static/templates/actions_popover_content.handlebars
index 469958be38..7a438467b0 100644
--- a/zephyr/static/templates/actions_popover_content.handlebars
+++ b/zephyr/static/templates/actions_popover_content.handlebars
@@ -4,7 +4,7 @@
     <a href="#" class="respond_button">
       <i class="icon-share-alt"></i>
       {{#if message.is_stream}}
-      Reply to this subject on stream <b>{{message.stream}}</b>
+      Reply to this topic on stream <b>{{message.stream}}</b>
       {{else}}
       Reply to this private message
       {{/if}}
@@ -22,7 +22,7 @@
     <li>
       <a href="#" class="popover_narrow_by_subject_button" data-msgid="{{message.id}}">
         <i class="icon-bullhorn"></i>
-        Narrow to this subject on stream <b>{{message.stream}}</b>
+        Narrow to this topic on stream <b>{{message.stream}}</b>
       </a>
     </li>
   {{else}}
diff --git a/zephyr/static/templates/message.handlebars b/zephyr/static/templates/message.handlebars
index 33666d33a4..dc8e66f5ee 100644
--- a/zephyr/static/templates/message.handlebars
+++ b/zephyr/static/templates/message.handlebars
@@ -39,7 +39,7 @@
             title="Narrow to stream &quot;{{display_recipient}}&quot;">{{display_recipient}}</span>
       &nbsp;<i class="icon-vector-narrow icon-vector-small"></i>&nbsp;
       <span class="message_label_clickable narrows_by_subject"
-            title="Narrow to stream &quot;{{display_recipient}}&quot;, subject &quot;{{subject}}&quot;">{{#if ../../../../use_match_properties}}{{{match_subject}}}{{else}}{{subject}}{{/if}}</span>
+            title="Narrow to stream &quot;{{display_recipient}}&quot;, topic &quot;{{subject}}&quot;">{{#if ../../../../use_match_properties}}{{{match_subject}}}{{else}}{{subject}}{{/if}}</span>
       {{#if your_empty_subject}}<i class="icon-vector-pencil edit_subject"></i>{{/if}}
       {{#each subject_links}}<a href="{{this}}" target="_blank"><i class="icon-vector-external-link-sign"></i>{{/each}}
     </td>
diff --git a/zephyr/static/templates/message_edit_form.handlebars b/zephyr/static/templates/message_edit_form.handlebars
index 5460839b83..fa7ee35a11 100644
--- a/zephyr/static/templates/message_edit_form.handlebars
+++ b/zephyr/static/templates/message_edit_form.handlebars
@@ -3,7 +3,7 @@
 <form id="message_edit_form" class="form-horizontal">
 {{#if is_stream}}
     <div class="control-group">
-        <label class="control-label edit-control-label" for="message_edit_subject">Subject</label>
+        <label class="control-label edit-control-label" for="message_edit_subject">Topic</label>
         <div class="controls edit-controls">
           <input type="text" value="{{subject}}" class="message_edit_subject" id="message_edit_subject">
         </div>
diff --git a/zephyr/static/templates/tutorial_home.handlebars b/zephyr/static/templates/tutorial_home.handlebars
index 5b70f0362e..f1eb89c19f 100644
--- a/zephyr/static/templates/tutorial_home.handlebars
+++ b/zephyr/static/templates/tutorial_home.handlebars
@@ -4,7 +4,7 @@
 
     <p>
         We show stream and private messages together, and time flows down. You
-        can "narrow" to a particular stream or subject by clicking on it.
+        can "narrow" to a particular stream or topic by clicking on it.
     </p>
 
     <div class="tutorial-done-button">
diff --git a/zephyr/static/templates/tutorial_message.handlebars b/zephyr/static/templates/tutorial_message.handlebars
index 12cf59d1a1..f10c8876e2 100644
--- a/zephyr/static/templates/tutorial_message.handlebars
+++ b/zephyr/static/templates/tutorial_message.handlebars
@@ -2,7 +2,7 @@
 
 <div class="tutorial-popover" id="tutorial-message">
     <p>
-        Messages in Zulip go to a <b>stream</b> and have a <b>subject</b>.
+        Messages in Zulip go to a <b>stream</b> and have a <b>topic</b>.
     </p>
 
     <div class="tutorial-done-button">
diff --git a/zephyr/static/templates/tutorial_reply.handlebars b/zephyr/static/templates/tutorial_reply.handlebars
index 86d68065ba..8f11269c4b 100644
--- a/zephyr/static/templates/tutorial_reply.handlebars
+++ b/zephyr/static/templates/tutorial_reply.handlebars
@@ -3,7 +3,7 @@
 <div class="tutorial-popover" id="tutorial-reply">
 
     <p>
-        You can reply to any message by clicking on it. The stream and subject
+        You can reply to any message by clicking on it. The stream and topic
         will automatically be filled in.
     </p>
 
diff --git a/zephyr/static/templates/tutorial_subject.handlebars b/zephyr/static/templates/tutorial_subject.handlebars
index 54fb03ea60..1020704881 100644
--- a/zephyr/static/templates/tutorial_subject.handlebars
+++ b/zephyr/static/templates/tutorial_subject.handlebars
@@ -3,7 +3,7 @@
 <div class="tutorial-popover" id="tutorial-subject">
 
     <p>
-        A subject is one word that describes what this message is about. Just
+        A topic is one word that describes what this message is about. Just
         like an e-mail subject line, only much shorter. Don't overthink it.
     </p>
 
diff --git a/zephyr/tests/frontend/tests/02-narrow.js b/zephyr/tests/frontend/tests/02-narrow.js
index e6e2c1804b..4099447e44 100644
--- a/zephyr/tests/frontend/tests/02-narrow.js
+++ b/zephyr/tests/frontend/tests/02-narrow.js
@@ -146,7 +146,7 @@ casper.then(function () {
 casper.then(function () {
     expect_home();
     casper.test.info('Narrowing by clicking subject');
-    casper.click('*[title="Narrow to stream \\\"Verona\\\", subject \\\"frontend test\\\""]');
+    casper.click('*[title="Narrow to stream \\\"Verona\\\", topic \\\"frontend test\\\""]');
 });
 
 casper.then(function () {