S: (adj) acute, discriminating, incisive, keen, knifelike, penetrating, penetrative, piercing, sharp (having or demonstrating ability to recognize or draw fine distinctions) "an acute observer of politics and politicians"; "incisive comments"; "icy knifelike reasoning"; "as sharp and incisive as the stroke of a fang"; "penetrating insight"; "frequent penetrative observations"
S: (adj) cutting, keen, knifelike, piercing, stabbing, lancinate, lancinating (painful as if caused by a sharp instrument) "a cutting wind"; "keen winds"; "knifelike cold"; "piercing knifelike pains"; "piercing cold"; "piercing criticism"; "a stabbing pain"; "lancinating pain"