Lewis & Short

ăcūlĕus, i, m. [acc. to Prisc. 618 P. dim. from 1. acus, with the gender changed, like diecula fr. dies, cf. Val. Prob. 1463 P.], a sting.

  1. I. Lit.
    1. A. Of animals: apis aculeum sine clamore ferre non possumus, Cic. Tusc. 2, 22; so Plin. 11, 17, 17: neparum, Cic. Fin. 5, 15 al.
      Also, the spur of fowls, Col. 8, 2, 8: locustarum, Vulg. Apoc. 9, 10.
    2. B. Of plants, a spine or prickle: spinarum, Plin. 13, 9, 19: carduorum, id. 20, 23, 99.
    3. C. Of an arrow or dart, the point, Liv. 38, 21, 11.
  2. II. Fig., a sting.
    1. A. Of a sharp, cutting remark: pungunt quasi aculeis interrogatiunculis, Cic. Fin. 4, 3; so id. Ac. 2, 31; id. Planc. 24 al.; Liv. 23, 42, 5.
    2. B. Of harsh treatment: aculeos severitatis judicum evellere, Cic. Clu. 55 fin.; so id. Cael. 12, 29.
    3. C. Of painful thought or care: meum ille pectus pungit aculeus, quid illi negoti fuerit ante aedīs meas, Plant. Trin. 4, 2, 158: domesticarum sollicitudinum, Cic. Att. 1, 18.