What is the antonym of word Keen which an adjective?

Here are some antonyms for "keen" as an adjective, depending on the specific meaning:

For "eager" or "enthusiastic":

* Indifferent

* Apathetic

* Uninterested

* Reluctant

* Unenthusiastic

* Disinclined

For "sharp" or "intense":

* Dull

* Blunt

* Weak

* Mild

* Unremarkable

For "intelligent" or "sharp-witted":

* Stupid

* Dull-witted

* Obtuse

* Unintelligent

* Slow

The best antonym will depend on the context in which "keen" is used.