irritation (n.)

early 15c., in physiology, in reference to sores and morbid swelling, from Middle French irritation 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.