1. (v. t.) To annoy; to inflame\; to render null and void.

2. (v. t.) To increase the action or violence of; to heighten excitement in; to intensify; to stimulate.

3. (v. t.) To excite anger or displeasure in; to provoke; to tease; to exasperate; to annoy; to vex; as, the insolence of a tyrant irritates his subjects.

4. (v. t.) To produce irritation in; to stimulate; to cause to contract. See Irritation, n., 2.

5. (n.) To make morbidly excitable, or oversensitive; to fret; as, the skin is irritated by friction; to irritate a wound by a coarse bandage.

6. (a.) Excited; heightened.

abrade afflict affront agent provocateur aggravate agonize ail alienate amplify anger annoy arouse augment bite bother bristle bug build up burn burn up chafe come between convulse crucify cut damage deepen deteriorate dilapidate disaffect distress disunite divide embitter endamage enhance enlarge enrage estrange exacerbate exasperate excruciate exercise fan the flame fester fluster fret gall get give pain gnaw grate grate on gravel grind gripe grit harass harm harrow harry hassle heat up hector heighten hot up huff hurt impair incense increase inflame inflict pain injure intensify irk jangle the nerves jar on kill by inches lacerate light the fuse magnify make acute make trouble make worse martyr martyrize miff nag needle nettle nip offend pain peeve pester pick at pick on pierce pinch pique pit against plague prick prolong the agony provoke put back put on edge put out put to torture rack rankle rasp rile roil rub ruffle separate set against set at odds set at variance set on set on edge set up sharpen sic on sour sow dissension stab sting stir the blood stir up stir up trouble torment torture trouble try tweak twist vex weaken work up worry worsen wound wring