Frown
late Middle English: from Old French froignier, from froigne ‘surly look’, of Celtic origin.
wiktionary
From Middle English frown, froun(“a threatening appearance; lowering of the clouds”), from frounen(“to frown”). See below.
From Middle English frounen(“to frown as an expression of disapproval, displeasure, shame, fear, or jealousy”), from Old French frognier(“to frown or scowl”), from Gaulish *frognā(“nostril”), from Proto-Celtic *srognā.
etymonline
frown (v.)
"contract the brows as an expression of displeasure," late 14c., from Old French frognier "to frown or scowl, snort, turn up one's nose" (preserved in Modern French refrogner), related to froigne "scowling look," probably from Gaulish *frogna "nostril" (compare Welsh ffroen "nose"), with a sense of "snort," or perhaps "haughty grimace." Figurative transitive sense "look with displeasure" is from 1570s. Related: Frowned; frowning.
frown (n.)
1580s, from frown (v.).
