1. That which causes irritation.

2. Irritating.

Nuttall's Standard dictionary of the English language By Nuttall, P.Austin

• irritance,
• irritans,
• irrogant,
• irrtants,
• irritaing,
• puritant,
• irritan,
• arrigant,
• irratant,
• irriting,
• irrevant,
• irrorant,
• iprotant,
• irrintant,
• irritat,
• irritantes,
• counterirrittant,
• irridenta,
• irrittant,
• floitant

• irridenta,
• irridentism,
• irritate,
• irridentist.

The adjective form of the word "irritant" is "irritating".

The plural of the "irritant" can be the "irritants".

The singular of the "irritant" can be the "irritant".