A term made by Majo Rika, specifically directed at Doremi Harukaze, later at the other
witch apprentices. It's a portmanteau consisting two Japanese terms. Ojama (お邪魔), meaning bothersome, hindrance, or intruding.
Majo (魔女), meaning
witch. Putting them together means Bothersome Witch-- an 'Ojamajo (おジャ魔女).
It is later adopted by other witches,
like Majo Rika's rival, Majo Ruka.