"wildly formed, of irregular proportions, boldly odd," c. 1600s, originally a noun (1560s), from French crotesque (16c., Modern French grotesque), from Italian grottesco, literally "of a cave," from grotta (see grotto). The explanation that the word first was used of paintings found on the walls of Roman ruins revealed by excavation (Italian pittura grottesca) is "intrinsically plausible," according to OED. Originally merely fanciful and fantastic, the sense became pejorative, "clownishly absurd, uncouth," after mid-18c. As the British name for a style of square-cut, sans-serif letter, from 1875. Related: Grotesquely; grotesqueness.