Unfair means not treating everybody by the same rules. An unfair advantage, that is unfair, unfair treatment.
The construction is unfair on or unfair to somebody. Common fixed phrases: unfair advantage, unfair dismissal — which is a specific legal claim in British employment law — and unfair competition. It is one of the earliest moral judgements children make and one of the last arguments adults abandon. Note unfairly, the adverb, and that unjust is the more formal word and is usually reserved for larger matters.
1adjectiveunfairNot treating everybody by the same rules.
“The whole arrangement was unfair and lasted nine years.”
synonyms: unjust, inequitable
unfair is a quality of injustice.
Also accepted in games: unjust
Old English unfaeger meant ugly — fair originally meant beautiful, and the sense of just came later. So unfair began as an insult about appearance and arrived at a complaint about rules.
Old English
unfæġer — ugly
Middle English
unfair — unattractive, unseemly
English, today
unfair
From Middle English unfair (“unattractive, unseemly”), from Old English unfæġer (“ugly”), equivalent to un- + fair.
Etymology from Wiktionary, CC BY-SA