The Collaborative International Dictionary
Macaca \Macaca\ prop. n. A genus of macaques including the rhesus monkey ( Macaca mulatta), much used in laboratory biomedical research. Formerly called Macacus.
Syn: genus Macaca.
Macaca mulatta \Macaca mulatta\ n. The rhesus monkey of South Asia; used in medical research.
Syn: rhesus, rhesus monkey.
Macaque \Ma`caque"\, n. [F. See Macacus.] (Zo["o]l.) Any one of several species of short-tailed monkeys of the genus Macaca (formerly Macacus), found in rocky regions of Asia and Africa; as, Macaca maurus, the moor macaque of the East Indies.
Note: Macaca mulatta is the Rhesus monkey, much used in biomedical research, and namesake of the Rh factor used in blood typing (due to discovery of that factor in the Rhesus monkey).