Keen1, a.
a. [compar. KEENER; superl. KEENEST.] [A-S. cēne, cēn, O. Sax. kôni, O. H. Ger. kuoni, M. H. Ger. küene, N. H. Ger. kühn, D. koen, O. Sw. kyn, kön, bold, stout, eager.]
Sense 1. Eager; vehement; sharp. “The sheep were so keen on the acorns.” L’Estrange. “Keen contest and destruction close allied.” Byron.
Sense 2. Sharp; having a fine, cutting edge; as, a keen razor, or a razor with a keen edge.
Sense 3. Piercing; penetrating; severe;—applied to cold, or to wind; as, a keen wind; the cold is very keen.
Sense 4. Bitter; piercing; acrimonious; as, keen satire or sarcasm.
Good father cardinal, cry thou amen To my keen curses. Shak.
Sense 5. Acute of mind; sharp; penetrating; as, a man of keen understanding; also expressing mental acuteness; as, a keen look; keen features.
☞ Keen is often used in the composition of words, the most of which are of very obvious signification; as, keen-edged, keen-eyed, keen-pointed, keen-sighted, keen-witted, and the like.