late 14c., remitten, "to forgive, pardon," from Latin remittere "send back, slacken, let go back, abate," from re- "back" (see re-) + mittere "to send" (see mission). Secondary senses predominate in English.
From c. 1400 as "refer for consideration or performance from one person or group to another;" early 15c. as "send to prison or back to prison." The meaning "allow to remain unpaid, refrain from exacting" (penalty, punishment, etc.) is from mid-15c. Meaning "send money (to someone) in payment" is recorded from 1630s. Related: Remitted; remitting.