Is it ensure, insure, or assure?
1620s, "equality," also "value of one currency in terms of another," from Latin par "equal, equal-sized, well-matched," also as a noun, "that which is equal, equality," of unknown origin. Watkins suggests perhaps from PIE root *pere- "to grant, allot," with suggestion of reciprocality (see part (n.)).
Another guess connects it with PIE root *per- "to traffic in, sell" (on notion of "give equal value for"); see pornography. Meaning "average or usual amount" is first attested 1767. Golf usage is first attested 1898. Figurative use of par for the course is from 1928.
"by, for," mid-13c., from Old French par, per, from Latin per (see per).
n. pl. par·tes (pär'tēz)
A part or portion of a structure, especially of an anatomical structure.
n. pl. pa·ri·a (pä'rē-ə)
A pair; specifically, a pair of cranial nerves.
ancient country in the southwestern part of Iran, roughly coextensive with the modern region of Fars. Its name was derived from the Iranian tribe of the Parsua (Parsuash; Parsumash; Persians), who settled there in the 7th century BC. Herodotus lists the leading Persian tribes as the Pasargadae, to which the Achaemenians, the royal family of Persia, belonged; the Maraphii; and the Maspii. It was these three that Cyrus II the Great assembled to approve his plans for his revolt against Astyages, his Median overlord, in 550 BC.