Omnivore:

In school, I learned 3, herbivore, omnivore and carnivore: and carnivores didn't or rarely ate plant matter. Yes I know domestic cats do, and wild ones might eat some grass to choke up a hair ball, but that's about it.

an organism that eats both plant and animal matter
(Cambridge English Dictionary)

one that is omnivorous.
(Merriam Webster)
feeding on both animal and vegetable substances (def of omnivorous in M Webster)

An organism that eats both plants and animals.
(American Heritage Dictionary)

(Zoology) an omnivorous person or animal
(Collins English Dictionary)

someone or something that is omnivorous.
(Random House Dictionary)
omnivorous from above dictionary. Eating food of any kind, including animals and plants.

an animal or person that eats food of both plant and animal origin.
(Google)

An omnivore is a kind of animal that eats either other animals or plants.
(Northwestern University)

An omnivore (/ˈɒmnɪvɔːr/) is an animal that has the ability to eat and survive on both plant and animal matter.[3] Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutrients and energy of the sources absorbed
(Wikipedia)

an animal that eats both plants and meat. An animal that only eats plants is called a herbivore and an animal that only eats meat is called a carnivore.
(MacMillan Dictionary)