Acumen

Webster's Practical Dictionary- A Practical Dictionary of the Englih Language · 1884 · p. 18

i-ku'men, n. Quickne of perception Aculeate Stem, or discernment; penetration of mind; acutene perspicuity. — Acu'minate, v. t. To render sharp or keen. — v.i. To end in a sharp point. — a. Having a long, tapering point. — Acu'mino us, a. Acuminate. — Acu'mina'tion, n. A sharpening; termination in, etc.