frown / froun/ • v. [intr.] furrow one's brow in an expression of disapproval, displeasure, or concentration: he frowned as he reread the letter. ∎  (frown on/upon) disapprove of: the old Russian rural system frowned on private enterprise.• n. a facial expression or look characterized by such a furrowing of one's brows: a frown of disapproval.DERIVATIVES: frown·er n.frown·ing·ly adv.ORIGIN: late Middle English: from Old French froignier, from froigne ‘surly look,’ of Celtic origin.

frown Produced primarily by the action of the corrugator muscle, which lowers the brows and pulls them together. In adolescents and adults, a vertical wrinkle often appears on the brow, and there may also be a horizontal wrinkle across the bridge of the nose.

Charles Darwin in his book The Expression of Emotion in Man and Animals called the corrugator the ‘muscle of difficulty’. Darwin was quite correct: frowning occurs with many kinds of difficulty, mental or physical. People who lift something very heavy will frown when doing so, as will people who are having a difficult time remembering something or figuring out the answer to a difficult mental task. Frowning is shown during concentration, perplexity, and determination to accomplish a difficult task. Darwin noted that lowering the brow provides a natural sunshade, and indeed people do frown when they are in bright sunlight without sunglasses.

When people frown, they are often perceived by others to be feeling unpleasant, resentful, or angry, although this is often not the case. This interpretation may occur because the frown is part of the anger expression, which also typically involves glaring eyes and tense lips.

Paul Ekman

frown vb. XIV. — OF. fro(i)gnier (surviving in renfrogner), f. froigne surly look, of Celt. orig. (cf. W. ffroen nose).