Old English uncynde "unnatural, not natural;" see un- (1) "not" + kind (adj.). Meaning "lacking in kindness" is recorded from mid-14c.
a thoughtless and unkind remark
unjustifiable
unjustified
unkempt
unkept
unkillable
unkind
unkindly
unkindness
unknit
unknowable
unknowing
