aculeus
  刺,螫刺
  A·cu·le·us n.; pl. Aculei
  1. Bot. A prickle growing on the bark, as in some brambles and roses.
  2. Zool. A sting.
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  aculeus
       n 1: a stiff sharp-pointed plant process
       2: a sharp-pointed process especially a sting of a
          hymenopterous insect