Aculeus
Pronunciation : A*cu"le*us
Part of Speech : n.; pl. Aculei.
Etymology : [L., dim. of acus needle.]
Definition : 1. (Bot.)
Defn: A prickle growing on the bark, as in some brambles and roses. Lindley.
2. (Zo?l.)
Defn: A sting.
Source : Webster's Unabridged Dictionary, 1913