rhesus

The term 'rhesus' has a purely literary origin, entering scientific vocabulary through a circuitous route. It was adopted by the French naturalist Jean-Baptiste Audebert in 1797 when he named the species Simia rhesus. He borrowed the name 'Rhesus' from Latin, which itself came from Greek mythology, where Rhesus was a Thracian king who fought in the Trojan War. There is no direct semantic link between the king and the monkey; Audebert likely chose the name arbitrarily from classical antiquity, a common practice in early taxonomic nomenclature. The word's modern meaning is thus entirely conventional, fixed by its use in biological classification.

The word is a simplex loanword. It originates from the Latin 'Rhesus', which was taken from Greek 'Rhēsos', the name of a mythical Thracian king. Its functional role is as a proper noun adopted as a common noun.