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Webster 1913 Edition

Verb.

[1st

un-

king

To cancel or annul what was done or sealed by a kiss; to cancel by a kiss.

[Obs.]

Let me

unkiss

the oath ’twixt thee and me.

Shakespeare

unkiss ‎(third-person singular simple present unkisses, present participle unkissing, simple past and past participle unkissed)

(obsolete) To cancel or annul something that was done or sealed with a kiss.

Richard II, Act V - Shakespeare

Let me unkiss the oath 'twixt thee and me.