Merriam-Webster's Collegiate® Dictionary, 11th Edition
NETTLE
I. noun
Etymology: Middle English, from Old English netel; akin to Old High German nazza nettle, Greek adikē Date: before 12th century any of a genus ( Urtica of the family Urticaceae, the nettle family) of chiefly coarse herbs armed with stinging hairs, any of various prickly or stinging plants other than the true nettles (genus Urtica ),
II. transitive verb (nettled; nettling)
Date: 15th century
to strike or sting with or as if with nettles, to arouse to sharp but transitory annoyance or anger, see: irritate