grimace

Concise Oxford English Dictionary © 2008 Oxford University Press:
grimace /grɪˈmeɪs, ˈgrɪməs/

▶noun an ugly, twisted expression on a person's face, typically expressing disgust, pain, or wry amusement. ▶verb make a grimace.

– derivatives
grimacer noun.

– origin C17: from Fr., from Sp. grimazo ‘caricature’, from grima ‘fright’.