an Aladdin's lamp
A magical object that allows its owner to make wishes and have them granted. (In The Arabian Nights, Aladdin finds a magic lamp in a cave.) The kids think that old ring they found in the attic is an Aladdin's lamp, but it's really just a piece of junk.
an Aladdin's lamp
a talisman that enables its owner to fulfil every desire. In the Arabian Nights tale of Aladdin, the hero finds a magic lamp in a cave. He discovers that rubbing it summons a powerful genie who is able to carry out all his wishes.