promise the moon
Also found in: Dictionary, Thesaurus, Medical, Legal.
promise the moon (to someone)and promise someone the moon
to make extravagant promises to someone. Bill will promise you the moon, but he won't live up to his promises. My boss promised the moon, but never gave me a raise.
promise (somebody) the moon(British, American & Australian) also promise (somebody) the earth (British & Australian)
to promise something impossible He had promised her the earth but five years later they were still living in the same small house.