grawlix /GRAW-lix/. noun. A series of typographic symbols used in place of an offensive word or phrase. Coined by Mort Walker in the satirical article “Let’s Get Down to Grawlixes” (which I can’t find online, thanks for $%@&#! nothing, Google) the term took off and has become a standard part of the lexicon of comics. As you can see for yourself, the grawlix originated as a mix of typographic and other symbols. See also: jarns, quimps, and nittles.
Sadly, most of Walker’s other awesome comic-related coinages failed the popularity test, including plewds (the flying sweat droplets that indicate hard work or stress), briffits (the clouds of dust that indicate the swift departure of a character), and squeans (the starbursts, circles and spirals that indicate dizziness or drunkenness).