Mashed means crushed to a soft pulp. No lumps, if you have done it properly.
Potatoes are what get mashed in Britain more than anything else, and mashed potato is such a fixture that mash on its own means it. Bananas and avocados get the same treatment. The tool is a masher and the verb is mash. There is an informal sense meaning drunk or exhausted, which is chiefly British. Sausage and mash is one of the fixed pairs of the English menu.
1adjectivemashedCrushed into a soft pulpy mass.
“He ate mashed potato and nothing else.”