any weedy plant of the temperate urticaceous genus Urtica, such as U. dioica (stinging nettle), having serrated leaves with stinging hairs and greenish flowers

any of various other urticaceous plants with stinging hairs or spines

any of various plants that resemble urticaceous nettles, such as the dead-nettle, hemp nettle, and horse nettle

to bother; irritate

to sting as a nettle does