Real Dictionary

white lie
countable noun: If you refer to an untrue statement as a white lie, you mean that it is made to avoid hurting someone's feelings or to avoid trouble, and not for an evil purpose.

white lie in American English
a lie concerning a trivial matter, often one told to spare someone's feelings
a minor, polite, or harmless lie; fib

white lie in British English
noun: a minor or unimportant lie, esp one uttered in the interests of tact or politeness