diff --git a/src/calibre/gui2/library/models.py b/src/calibre/gui2/library/models.py
index 7e5b681bc4..37259b6214 100644
--- a/src/calibre/gui2/library/models.py
+++ b/src/calibre/gui2/library/models.py
@@ -926,13 +926,19 @@ class BooksModel(QAbstractTableModel):  # {{{
                 return None
             if role == Qt.ToolTipRole:
                 ht = self.column_map[section]
+                fm = self.db.field_metadata[self.column_map[section]]
                 if ht == 'timestamp':  # change help text because users know this field as 'date'
                     ht = 'date'
-                if self.db.field_metadata[self.column_map[section]]['is_category']:
-                    is_cat = '.\n\n' + _('Click in this column and press Q to Quickview books with the same %s') % ht
+                if fm['is_category']:
+                    is_cat = '\n\n' + _('Click in this column and press Q to Quickview books with the same %s') % ht
                 else:
                     is_cat = ''
-                return (_('The lookup/search name is "{0}"{1}').format(ht, is_cat))
+                cust_desc = ''
+                if fm['is_custom']:
+                    cust_desc = fm['display'].get('description', '')
+                    if cust_desc:
+                        cust_desc = '\n' + _('Description:') + ' ' + cust_desc
+                return (_('The lookup/search name is "{0}"{1}{2}').format(ht, cust_desc, is_cat))
             if role == Qt.DisplayRole:
                 return (self.headers[self.column_map[section]])
             return None
diff --git a/src/calibre/gui2/preferences/create_custom_column.py b/src/calibre/gui2/preferences/create_custom_column.py
index 5f0212b96b..225116ad18 100644
--- a/src/calibre/gui2/preferences/create_custom_column.py
+++ b/src/calibre/gui2/preferences/create_custom_column.py
@@ -145,6 +145,7 @@ class CreateCustomColumn(QDialog, Ui_QCreateCustomColumn):
             self.use_decorations.setChecked(c['display'].get('use_decorations', False))
         elif ct == '*text':
             self.is_names.setChecked(c['display'].get('is_names', False))
+        self.description_box.setText(c['display'].get('description', ''))
 
         self.composite_contains_html.setToolTip('<p>' +
                 _('If checked, this column will be displayed as HTML in '
@@ -312,6 +313,7 @@ class CreateCustomColumn(QDialog, Ui_QCreateCustomColumn):
 
         if col_type in ['text', 'composite', 'enumeration'] and not is_multiple:
             display_dict['use_decorations'] = self.use_decorations.checkState()
+        display_dict['description'] = self.description_box.text().strip()
 
         if not self.editing_col:
             self.parent.custcols[key] = {
diff --git a/src/calibre/gui2/preferences/create_custom_column.ui b/src/calibre/gui2/preferences/create_custom_column.ui
index 54fae6a150..b9fa29fe9b 100644
--- a/src/calibre/gui2/preferences/create_custom_column.ui
+++ b/src/calibre/gui2/preferences/create_custom_column.ui
@@ -151,6 +151,23 @@ Everything else will show nothing.</string>
          </item>
         </layout>
        </item>
+       <item row="3" column="0">
+        <widget class="QLabel" name="label_31">
+         <property name="text">
+          <string>D&amp;escription</string>
+         </property>
+         <property name="buddy">
+          <cstring>description_box</cstring>
+         </property>
+        </widget>
+       </item>
+       <item row="3" column="2">
+        <widget class="QLineEdit" name="description_box">
+         <property name="toolTip">
+          <string>Optional text describing what this column is for</string>
+         </property>
+        </widget>
+       </item>
        <item row="4" column="2">
         <layout class="QHBoxLayout" name="horizontalLayout_3">
          <item>
diff --git a/src/calibre/gui2/tag_browser/model.py b/src/calibre/gui2/tag_browser/model.py
index ccdd807e77..edcd7eac4d 100644
--- a/src/calibre/gui2/tag_browser/model.py
+++ b/src/calibre/gui2/tag_browser/model.py
@@ -333,7 +333,13 @@ class TagsModel(QAbstractItemModel):  # {{{
             elif key == 'news':
                 tt = ''
             else:
-                tt = _(u'The lookup/search name is "{0}"').format(key)
+                cust_desc = ''
+                fm = self.db.field_metadata[key]
+                if fm['is_custom']:
+                    cust_desc = fm['display'].get('description', '')
+                    if cust_desc:
+                        cust_desc = '\n' + _('Description:') + ' ' + cust_desc
+                tt = _(u'The lookup/search name is "{0}"{1}').format(key, cust_desc)
 
             if self.category_custom_icons.get(key, None) is None:
                 self.category_custom_icons[key] = (