Old World monkey; cercopithecoid; guenon
Refers to any monkey of the family Cercopithecidae, especially the guenons (genus Cercopithecus). Typically used in zoological contexts.
I saw a troop of Old World monkeys at the zoo.
Katakana spelling is common for animal names and is the usual written form for this word.
Kanji spelling is rare and mainly found in older or specialized texts.
Compound of 尾長 (onaga, 'long-tailed') + 猿 (saru, 'monkey'), referring to the long tail characteristic of many species in this group.