frown (v.) Look up frown at
"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.) Look up frown at
1580s, from frown (v.).