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.
any food produced irritation of the stomach
irritability
irritable
irritant
irritate
irritating
irritation
irrumation
irrupt
irruption
IRS
Irwin