Definition of keen

• superl. - Sharp; having a fine edge or point; as, a keen razor, or a razor with a keen edge.
• superl. - Acute of mind; sharp; penetrating; having or expressing mental acuteness; as, a man of keen understanding; a keen look; keen features.
• superl. - Bitter; piercing; acrimonious; cutting; stinging; severe; as, keen satire or sarcasm.
• superl. - Piercing; penetrating; cutting; sharp; -- applied to cold, wind, etc, ; as, a keen wind; the cold is very keen.
• superl. - Eager; vehement; fierce; as, a keen appetite.
• v. t. - To sharpen; to make cold.
• n. - A prolonged wail for a deceased person. Cf. Coranach.
• v. i. - To wail as a keener does.