With emacs-lisp-mode make a comment that includes character sequences enclosed
by tick ` and a single quote ' .

The character sequence within gets highlighted with a different colour than the
usual typeface for comments.

Example:

;; Insert `cog', `col', `com', `con', `cor', `coun', `cum'.

The character sequences cog, col, com, con, cor, coun, and cum get highlighted

But if the character sequence within tick ` and a single quote ' is a single
character, the character does not get highlighted.

Example:

;; Insert `k' for words with initial values.

The character k does not get highlighted.