Which is the name for the typographical comments that cartoonists use for curse words?

The term 'grawlix' refers to the series of typographical symbols (such as @#$%&!) used in cartoons and comic strips to represent swear words. Also known as 'jarns', 'nittles', and 'obscenicons, 'grawlixes' usually appear in 'maledicta balloons' alongside the comic characters who are uttering the oaths.

These terms were the creation of the cartoonist Mort Walker, by which he meant a comic-strip balloon containing symbols to indicate profanity. He first used them in 1964 in an article he wrote for the National Cartoonists Society in the US. He included it in his 1980 book 'The Lexicon of Comicana', a satire on cartoonists’ comic devices, which ironically became a textbook for many art students.

Walker was quoted as saying, "It started out as a joke for the National Cartoonists Society magazine. I spoofed the tricks cartoonists use, like dust clouds when characters are running or lightbulbs over their heads when they get an idea." Under the heading of 'maledicta', Walker included four terms for graphically euphemistic devices, such as 'jarns', 'quimps', 'nittles' and 'grawlixes'.

It would be hard to define a 'grawlix' in a way that adequately distinguishes it from the others, though his illustration for it is of what he calls “ostensibly obliterated epithets”, or "scribbled-out words". Presently, 'grawlix' is the most commonly used term to describe this form of expression by comic strip writers and cartoonists.