Uke is a slur used to describe Ukrainians in a derogatory way. Short form of Ukrainian, not derogatory, commonly used by Ukrainians to refer to themselves or one another.
The word Uke is a racial slur that has been used historically to degrade and dehumanize ukrainians. The word is still used by some people for this purpose, and it is seen as offensive and hurtful to ukrainians. If you are unsure about whether or not it is appropriate to use the word Uke, it is best to err on the side of caution and avoid using it in any situation.