As a noun, from 1640s as "member of an independent congregational church, English Congregationalist." It is attested from 1670s as "one who acts according to his own will" and 1808 in the specific sense "person not acting as part of a political party."
An Old English word for it was selfdom, with self + dom "law," but in form this is closer to privilege (n.). The two concepts are not always distinguishable.
1755 as a term in philosophy, "a way of thinking which explains phenomena by the assumption of two independent and absolute elements," from French dualisme (1754); see dual + -ism. Theological sense of "doctrine of two independent divine beings or eternal principles" is by 1847. General sense of "division into two" is by 1831.
ancient realm in northwestern South America, later a Spanish viceroyalty, since 1821 an independent republic, from Spanish Peru, said to be from Quechua (Inca) pelu "river." Related: Peruvian.
1960, in computing, "sequence of one or more characters used to specify the beginning or end of separate, independent regions in text or other data streams," agent noun from delimit.