keen Copy link Outline 1. ācer, cris, cre (in most applications)2. perspĭcax (sharp, penetrating)3. subtīlis, e (fine, subtle, discriminating)4. săgax (keen-scented; fig. shrewd)5. ăcerbus (cutting, painful) • keen: 1. ācer, cris, cre (in most applications): k. winter, a. hiems, Hor. Od. 1, 4, 1: the k.est of all the senses, acerrimus ex omnibus sensibus, Cic. de Or. 2, 87, 357. 2. perspĭcax (sharp, penetrating): how k. he is about all these things, ad has res quam sit p., Ter. Heaut. 2, 3, 129. Join: astutus, perspicax, ib. 5, 1, 1; acutus et perspicax, Cic. Off. 1, 28, 100. 3. subtīlis, e (fine, subtle, discriminating): k. criticism, s. judicium, Cic. Fam. 15, 6. 4. săgax (keen-scented; fig. shrewd): very k. in suspecting, sagacissimus ad suspicandum, Cic. Cat. 1, 8, 19. 5. ăcerbus (cutting, painful): k. grief, luctus a. Tib. 2, 6, 41. Phr.: to form very k. conjectures about the future, callidissime de futuris conjicere, Nep. Them. 1: to have a very k. sense of smell, sagacissime olfacere, Plin. 11, 37, 50. See also acute, poignant.