an olive is ‘pitted’: adjective or verb? [closed]

‘pitted olives’, peeled carrots’, ‘cobbed corn’

I mean, at first glance they’re of course adjectives followed by nouns; but are they? Isn’t the word ‘pitted’ in this case describing the action taken upon the olive?

Do we assume it’s an adjective because it’s written on an object found in the grocery store?

They're adjectives. The action of removing an olive's pit is "pitting", and an olive that has been pitted is called a pitted olive. You can further tell that this is an adjective by its purpose for appearing on the label, which is to distinguish these olives by describing them. Also by noting that no one or nothing is actually performing any action; the label is simply telling you that the olives are pitted, not that "[name or thing unknown] once pitted them". Adjectives which describe the action of a verb frequently take the same form as the verb's past tense. That doesn't make them any less adjective. See "the dotted line", "the ruined house", or "the sealed door", where all the descriptors fit the pattern and are very, very clearly adjectives.