Emanata was coined by the American cartoonist Mort Walker (born 1923), creator of the long-running comic strips Beetle Bailey and Hi and Lois. In his Lexicon of Comicana, (1980), Walker introduced a number of invented words, including:
Plewds: teardrop shapes emanating from a character's head to express embarrassment or worry.
Blurgit: a combination of symbols expressing speed and action.
Neoflects: short, straight lines around an object to indicate that it's brand-new.
Jarns, quimps, nittles, and grawlixes: the squiggles, stars, and other glyphs that substitute for curse words.
Although the Lexicon of Comicana was originally written as a satire of cartoonists' stock devices, it's used today as a textbook for art students.
Image from Lexicon of Comicana.