Irritation

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late Middle English: from Latin irritatio(n- ), from the verb irritare (see irritate).

wiktionary

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Borrowed from Middle French irritation, from Latin irrītātiō, from irrītāre, present active infinitive of irrītō(“I excite”)

etymonline

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irritation (n.)

early 15c., irritacioun, in physiology, in reference to sores and morbid swelling, from Old French irritacion or directly from Latin irritationem (nominative irritatio) "incitement, stimulus; irritation, wrath, anger," noun of action from past-participle stem of irritare "to excite, provoke" (see irritate). Meaning "impatient or angry excitement" is from 1703.