trench·ant 
(trĕnchənt)
(trĕnchənt)adj.
1. Forceful and clear; penetrating: a trenchant argument.
2. Caustic; cutting: a trenchant wit.
3. Distinct; clear-cut: "The times were felt to require ... trenchant distinctions between good and bad, right and wrong" (David Simpson).
[Middle English, from Old French, cutting, from present participle of trenchier, to cut; see TRENCH.]
trenchan·cy n.
trenchant·ly adv.