jigger

(noun) a small glass adequate to hold a single swallow of whiskey. Synonyms: shot glass, pony.

(noun) any small mast on a sailing vessel; especially the mizzenmast of a yawl. Synonyms: jiggermast.

(noun) larval mite that sucks the blood of vertebrates including human beings causing intense irritation. Synonyms: harvest mite, chigger, redbug.