adjective

keen

Translation

eager, enthusiastic, sharp, intense

He is keen on learning new languages.

She has a keen sense of smell.

The knife has a very keen edge.

There is keen competition for the job.

be keen on (sth./-ing) to be very interested in or enthusiastic about (sth.) He is keen on learning new languages.

be keen to (to-inf) to be very eager to do (sth.) She was keen to start the project.

a keen (noun) sharp or acute She has a keen sense of smell.

Synonyms: eager, sharp, acute; Antonyms: dull, apathetic, reluctant

From Old English 'cēne' meaning 'bold, wise'. It evolved to mean sharp or enthusiastic.

Think of a 'keen' eagle's eye, which is very sharp, or being 'keen' on an idea, meaning you're very enthusiastic about it.