incisive

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Penetrating, clear, and sharp, as in operation or expression.

from The Century Dictionary.

• Having the quality of cutting into or dividing the substance of anything; cutting, or used for cutting: as, the incisive teeth.
• Figuratively, sharply and clearly expressive; penetrating; trenchant; sharp; acute.
• Having the power of breaking up or dissolving viscid or coagulated humors.
• In anatomy and zoology: Having the character, function, or situation of an incisor tooth; incisorial.
• Pertaining in any way to an incisor; situated near incisors; containing incisors: synonymous with premaxillary or intermaxillary and prepalatine.
• noun In entomology, the incisive edge of the mandible of a beetle. See incisive edge, above.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Having the quality of incising, cutting, or penetrating, as with a sharp instrument; cutting
• adjective (Anat.) Of or pertaining to the incisors; incisor.
• adjective Clearly and succinctly stated, with penetrating insight into the issue at hand.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Quickly proceeding to judgment and forceful in expression; decisive; forthright.
• adjective Intelligently analytical and concise.
• adjective Having the quality of incising, cutting, or penetrating, as with a sharp instrument; sharp; acute; sarcastic; biting.
• adjective anatomy Of or relating to the incisors.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective having or demonstrating ability to recognize or draw fine distinctions
• adjective suitable for cutting or piercing