The simple, dictionary, definition is "a member of the order Primates". That's obviously a circular, and rather unhelpful, definition, but, then dictionaries aren't the same thing as encyclopaedias. But even it requires picking apart a bit. For a start, note the capital 'P' in the word "Primates". This indicates it's the name of a discrete thing, and not just the plural of the word "primate". It's a Latinate word, like "Rodentia" for the order of rodents or "Proboscidea" for the order of elephants and their extinct kin. Which means that it may not be pronounced the way you think; it has three syllables: Prime-ATE-eez. It literally means "of the first rank", because, you know, anything with us in it has to be of the highest rank. (Hence the title "primate" given to some high-ranking bishops).