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")
incisive -- (suitable for cutting or piercing; "incisive teeth")