When young and white, this mushroom may be known as common mushroom, white mushroom, button mushroom, cultivated mushroom, table mushroom, and champignon mushroom (or simply champignon). When young and brown, it may be known as Swiss brown mushroom, Roman brown mushroom, Italian brown mushroom, cremini/crimini mushroom,[ chestnut mushroom (not to be confused with Pholiota adiposa), and baby bella.
When marketed in its mature state, the mushroom is brown with a cap measuring 10–15 centimetres (4–6 inches).
This form is commonly sold under the names portobello mushroom, portabella mushroom, and portobella mushroom, but the etymology is disputed.
