What is Retire?

Legal Definition
An applied to Mils of exchange, this word is ambiguous. It is commonly used of an endorser who takes up a bill by handing the amount to a transferee, after which the endorser holds the instrument with all his remedies intact. But it is sometimes used of an acceptor, by whom, when a blll is token up or retired at maturity, it is in effect paid, and all the remedies on it extinguished. Byles, Blils, 215. See Eisam v. Denny, 15 C. B. 94.
-- Black's Law Dictionary
Legal Definition
To take up negotiable paper by one of the parties liable thereon, either with intent to withdraw it from circulation or to hold it and retain his remedies against prior parties.
-- Ballentine's Law Dictionary