Webster's Revised Unabridged Dictionary · 1913

Unfair

Unfair , transitive verb

[1st pref. un- + fair.]

To deprive of fairness or beauty. [Rare] — Shakespeare

Unfair , adjective

[Anglo-Saxon unfager unlovely. See Un- not, and Fair, a.]

Not fair; not honest; not impartial; disingenuous; using or involving trick or artifice; dishonest; unjust; unequal.
You come, like an unfair merchant, to charge me with being in your debt. — Swift