Being keen on something refers to having a strong interest or enthusiasm for it. The antonyms for being keen on can be disinterested, unenthusiastic, indifferent, apathetic, unconcerned, and bored. Disinterested refers to having no interest or concern in something, and unenthusiastic means lacking enthusiasm or passion. Indifferent means having no preference or bias, while apathetic refers to a lack of emotion or feeling. Unconcerned suggests a lack of care or interest, and bored means feeling uninterested or tired of something. Being keen on something implies a positive attitude towards it, and the opposite of it represents negativity or lack of interest.