1) Enation 2) Plant process 
• (n.) A prickle growing on the bark, as in some brambles and roses. • (n.) A sting.
<botany> A prickle growing from bark. ... (15 Jan 1998) ... 
A·cu'le·us noun ; plural Aculei [ Latin , dim. of acus needle.] 1. (Botany) A prickle growing on the bark, as in some brambles and roses. Lindley. 2. (Zoology) A sting. 
[n] - a stiff sharp-pointed plant process 2. [n] - a sharp-pointed process especially a sting of a hymenopterous insect
aculeus 1. The sting of an insect or other animal.2. A conical elevation of the skin of a plant, becoming hard and sharp-pointed: as with the rose.3. A hair-like projection.
noun a sharp-pointed process especially a sting of a hymenopterous insect
the curved stinger arising distally from the telson vesicle. The aculeus is hollow and bears a small distal opening to allow venom from the internal venom glands of the vesicle to be injected for predation or defense.
the actual hypodermic needle-like singer on the Telson.
the modified ovipositor or sting of certain hymenopterous insects. · prickle (def. 2).