Magnus, great; magnificent, magniloquent, magnify.
Malus, bad; malady, malice, maltreat.
Maneo (mans-um), I remain; mansion, permanent.
Manus, the hand; manufacture, manual, manuscript.
Mare, the sea; marine, mariner.
Mater, a mother; maternal, matricide.
Maturus, ripe; mature, maturity.
Medeor, I heal; medicine, remedy.
Medius, the middle; medial, immediate, Mediterranean.
Memini, I remember; memor, mindful; memorable, commemorate, memento, immemorial.