Chewed means to eat and break down food with your teeth until it's soft and easy to swallow.
When we talk about something being chewed, it usually refers to eating. For example, if you ate a big piece of gum or a hard candy, it might have been difficult for you to chew properly. You could also be talking about someone who chews their nails or food while they're nervous or bored - in this case, the word is being used more like an action that people do out of habit.
To crush with the teeth by repeated closing and opening of the jaws; done to food to soften it and break it down by the action of saliva before it is swallowed.
Example: Make sure to chew thoroughly, and don't talk with your mouth full!
That has been chewed; masticated.
