Noun

(en noun)

The act of irritating, or exciting, or the state of being irritated; excitement; stimulation, usually of an undue and uncomfortable kind; especially, excitement of anger or passion; provocation; annoyance; anger.

* {{quote-magazine, year=2012, month=March-April

, author=Anna Lena Phillips , title=Sneaky Silk Moths , volume=100, issue=2, page=172 , magazine=(American Scientist) citation , passage=Last spring, the periodical cicadas emerged across eastern North America. Their vast numbers and short above-ground life spans inspired awe and irritation in humans—and made for good meals for birds and small mammals.}}

The act of exciting, or the condition of being excited to action, by stimulation; -- as, the condition of an organ of sense, when its nerve is affected by some external body; especially, the act of exciting muscle fibers to contraction, by artificial stimulation; as, the irritation of a motor nerve by electricity; also, the condition of a muscle and nerve, under such stimulation.

A condition of morbid excitability or oversensitiveness of an organ or part of the body; a state in which the application of ordinary stimuli produces pain or excessive or vitiated action.

Noun

(en noun)

A pushing or goading toward action.

An activity causing excitement or pleasure.

(biology) Any action or condition that creates a response; sensory input.