keen

(verb): To make cold, to sharpen.
(adjective): Often with a prepositional phrase, or with to and an infinitive: showing a quick and ardent responsiveness or willingness; eager, enthusiastic, interested.
(adjective): Fierce, intense, vehement.
(adjective): Having a fine edge or point; sharp.
(adjective): Acute of mind, having or expressing mental acuteness; penetrating, sharp.
(adjective): Acrimonious, bitter, piercing.
(adjective): Of cold, wind, etc.: cutting, penetrating, piercing, sharp.
(adjective): Of prices, extremely low as to be competitive.
(adjective): Marvelous.
(adjective): Brave, courageous; audacious, bold.