> A harmless lie
> A small or unimportant lie
> A lie that that is meant to spare someone’s feelings
> To lie about a small or unimportant matter
White is often associated with something which is innocent / harmless and hence it is prefixed with lie to derive this meaning.
Sometimes it is better to tell a white lie than to hurt someone’s feelings.
Many times a white lie can seem the ideal tool to keep the things around you balanced.