Green’s Dictionary of Slang

(US) a style of facial whisker, grown on the upper part of the cheek only.

1920

C. Sandburg ‘Alley Rats’ in Smoke and Steel 20: They were calling certain styles of whiskers by the name of ‘lilacs.’ / And another manner of beard assumed in their chatter a verbal guise / Of ‘mutton chops,’ ‘galways,’ ‘feather dusters’.