Le pain

(le) pain = bread
(la) mie (pronounced 'mee') = the inside of the bread, when the crust is removed
(la) croûte (pronounced 'croot') = the crust
(le) croûton = the tip of a bread, or a crouton

le pain de mie = sliced bread
se vendre comme des petits pains= to sell like hot cakes (literally like small breads)
ça ne mange pas de pain = it doesn't cost anything (literally it doesn't eat bread)
je ne mange pas de ce pain-là = I won't have anything to do with it (literally I don't eat that kind of bread)

(un) pain is also slang for a punch, as in:
je lui ai mis un pain = I punched him