Primate
wiktionary
From French primate[1876], from Latin primas(“one of the first, chief, excellent, noble”). So named due to the belief that primates are the “highest” order of mammals/animals.
From Middle English primate, primat, from Old French primat, from a noun use of Latin primat-, from primas, alternative form of primus(“prime, first rank”). Compare English primus, of similar derivation and meaning. [circa 1200]
etymonline
primate (n.)
"high bishop, preeminent ecclesiastical official of a province," having a certain jurisdiction, as vicar of the pope, over other bishops in his province, c. 1200, from Old French primat and directly from Medieval Latin primatem (nominative primas) "church primate," noun use of Late Latin adjective primas "of the first rank, chief, principal," from primus "first" (see prime (adj.)).
The meaning "animal of the biological order including monkeys and humans" is attested from 1876, from Modern Latin Primates, the order name (Linnæus), from plural of Latin primas; so called for being regarded as the "highest" order of mammals (originally also including bats).
