incisive
     adj 1: 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" [syn: {acute}, {discriminating}, {keen},
             {knifelike}, {penetrating}, {penetrative}, {piercing},
             {sharp}]
     2: very penetrating and clear and sharp in operation; "an
        incisive mind"; "a keen intelligence"; "of sharp and
        active intellect" [syn: {keen}, {sharp}]
     3: suitable for cutting or piercing; "incisive teeth"; "the
        piercing needle" [syn: {piercing}]
Source: WordNet® 2.0