un- + fair

source: Isn't this a little bit unfair, I mean we have guns and they only have swords | Anime / Manga | Know Your Meme

not based on or behaving according to the principles of equality and justice:

【人に】不公平な, 偏った «to, on»

e.g. at times like these the legal system appears inhumane and unfair.

unkind, inconsiderate, or unreasonable:

不正な, 不当な, ずるい

e.g. you're unfair to criticize like that when she's never done you any harm.

not following the rules of a game or sport.

Old English unfæger‘not beautiful’(see un-1, fair1).