Manimission, in Roman antiquity, the form by which slaves, or other persons not sui juris, were released from their condition. There were three modes of effecting a legal release, by vindicta, census, or will, by any of which the freedman might obtain the rights of a citizen. The vindicta was the oldest, and as follows: The owner brought his slave before the magistrate, and stated the grounds on which he intended his manumission. The lictor laid a rod on the head of the slave, and declared him free by right of the Quirites; the master, who in the mean time held the slave, pronouncing the words, "I wish this man to be free," turned him round, and let him go (emisit e manu, whence the term). The magistrate then declared him to be free. The manumission by census was effected by the slaves giving in their names at the lustral census at the bidding of their masters. By will a slave could be made free conditionally or unconditionally, or free and an heir to the testator. Laws at different periods enacted restrictions, such as limiting the proportion of slaves a man might manumit in his will and preventing manumission to defraud creditors.

The act of manumission established the relation of patron and freedman between the manumittor and the manumitted; and if the former was a citizen, the latter became a member of his gens, and assumed his family as well as personal name, to which he added some other as surname, commonly that by which he was previously known.