THORN Copy link • THORNPROP., spina (a thorn or prickle on plants; also the thorn-bush): sentis: vepres (a brier). Black thorn, prunus silvestris (Cels.): Glastonbury thorn, *crataegus (Linn.): of thorns, made of thorn, spineus. Figuratively, spina, molestia: cura. To be a thorn in the side of anybody, alicui invisum or odiosum esse; aliquem pungere, urere: I am a thorn in your side, stimulus ego nunc sum tibi (Cornicè).