noun
Refers to a substance or thing that stimulates or excites the body, mind, or a system. Can be used for both positive stimulation and irritation.
カフェインは代表的な刺激物の一つです。
Caffeine is one of the typical stimulants.
この化粧品は刺激物を含まないので敏感肌で
This cosmetic does not contain irritants, so it can be used even on sensitive skin.
刺激 is the abstract noun for 'stimulus' or 'stimulation', while 刺激物 specifically refers to a concrete substance or thing that causes stimulation.
Compound of 刺激 (stimulus) + 物 (thing). The kanji 刺戟物 is a rare variant using 戟 for the second character.