Spamming the same comment I already made: If monkey is to be used as a scientific term instead of just a colloquial one, then apes are necessarily monkeys because everything they’re descended from is a monkey. Without apes included, “monkey” is paraphyletic. Apes and Old World monkeys are more closely related to each other than either are to New World monkeys.
Colloquially, "monkey" is already used to refer to apes all the time, so the linguistic argument is just a matter of preference and either usage is fine.
Spamming the same comment I already made: If monkey is to be used as a scientific term instead of just a colloquial one, then apes are necessarily monkeys because everything they’re descended from is a monkey. Without apes included, “monkey” is paraphyletic. Apes and Old World monkeys are more closely related to each other than either are to New World monkeys.
Colloquially, "monkey" is already used to refer to apes all the time, so the linguistic argument is just a matter of preference and either usage is fine.