Irritant

adj. causing irritation, causing annoyance; causing inflammation or extreme sensitivity (Medicine)

n. substance that causes irritation

The word irritant may refer to: Something that causes irritation, often a chemical substance.Irritant, a 2002 psychedelic trance album by X-Dream.IRRITANT - A Progressive rock band from Gloucester
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Noun
1. something that causes irritation and annoyance; "he's a thorn in my flesh"
(synonym) thorn
(hypernym) annoyance, bother, botheration, pain, infliction, pain in the neck, pain in the ass
(derivation) annoy, rag, get to, bother, get at, irritate, rile, nark, nettle, gravel, vex, chafe, devil

adj. irritant, aggravating, annoying; irksome, jumpy; galling, angering

v. irritate, annoy; pique, anger; gall, nettle, chafe, ruffle

(n.)
That which irritates or excites.
  

(n.)
Any agent by which irritation is produced; as, a chemical irritant; a mechanical or electrical irritant.
  

(n.)
A poison that produces inflammation.
  

(a.)
Rendering null and void; conditionally invalidating.
  

(a.)
Irritating; producing irritation or inflammation.