You do not have to agree with the definition, but I have to use one :)
I think it is crystal clear and leaves no room for considerations hehe If the animals eat both plants and meat, naturally, and can digest both, it is an omnivore!
Monkeys are not frugivores. Some spices can be frugivores , one is even herbivoric, but most of them are omnivores. They eat lizards, insects & spiders, bird eggs, some even hunt larger game or eat other monkeys! This has only to do with biochemical digestion capacities, not physiology, as well as choice of food sources of course :)
The most common frugivores are birds, how does that relate to your definition based on physiology. It again , has nothing to do with this!
Pigs, birds, bears, dogs, lizards, tortoises, monkeys, humans, coyotes etc etc have only 1 thing common often, that is being omnivores :)
Definition of omnivore
: one that is omnivorous Bears and coyotes are omnivores.
https://www.merriam-webster.com/dictionary/omnivore
Some birds are omnivores some carnivores some herbivores it has nothing to do with physiology.
But if you change the definition to omnivore = a certain physiological type, monkeys, then we are simply talking bout primates and their physiology in general, and we are at a very different type of classification!
Lets see what Cambridge thinks:
A few tortoise species, such as the redfoot tortoise, are omnivores, which means they eat everything!
an animal that is naturally able to eat both plants and meat
https://dictionary.cambridge.org/dictionary/english/omnivore
Peace
Lol 😀 chimps eat 50-90 % fruit in the wild depending on who you believe. They are supposedly the closest to us genetically.
Which in my eyes makes humans possible frugivores, not a typical omnivore that we have been taught all our lives.
Other considerations:
Humans cannot tear apart uncooked meat, babies crave fruit, we have a sweet tooth plus so many physical things that humans have adapted for and not adapted physically for digesting meat or digesting vegetables.