unkindly (adj.) Look up unkindly at Dictionary.com
early 13c., "not natural, unnatural," from un- (1) "not" + kindly (adj.). From c.1300 as "without natural affection, unfraternally." Old English had ungecyndelic.
unkindly (adv.) Look up unkindly at Dictionary.com
c.1200, "unsuitably, improperly," from un- (1) "not" + kindly (adv.). From mid-15c. as "discourteously, maliciously."