adjective Often with a prepositional phrase, or with to and an infinitive: showing a quick and ardent responsiveness or willingness; eager, enthusiastic, interested.
I’m keen on computers.
adjective Fierce, intense, vehement.
This boy has a keen appetite.
adjective Having a fine edge or point; sharp.
adjective Acute of mind, having or expressing mental acuteness; penetrating, sharp.
adjective Acrimonious, bitter, piercing.
keen satire or sarcasm
adjective Cutting, penetrating, piercing, sharp.
a keen wind
adjective Of prices, extremely low as to be competitive.