'To take the name of God in vain' definitions:

Definition of 'To take the name of God in vain'

From: GCIDE

Vain \Vain\, n. Vanity; emptiness; -- now used only in the phrase
in vain. [1913 Webster]
For vain. See In vain. [Obs.] --Shak.
In vain, to no purpose; without effect; ineffectually. " In vain doth valor bleed." --Milton. " In vain they do worship me." --Matt. xv. 9.
To take the name of God in vain, to use the name of God with levity or profaneness. [1913 Webster]