n.

1. 激怒，惱怒，生氣[U][（+at/with）]
   He could not hide his irritation that he had not been invited.

   他無法掩飾因未被邀請而生的氣惱。

2. 刺激物；惱人事[C]
3. 【醫】刺激；過敏；疼痛；發炎[U][C]
   The irritation stops when I take my shoes off.

   我脫下鞋子，疼痛不適之感就會消失。