v. phr. 1. To call upon (God) as a witness to your truth or honesty when you are lying; swear by (God) untruthfully. You shall not take the name of the Lord your God in vain. 2. informal To talk about a person or mention his name. "Did I hear someone taking my name in vain?" asked Bill as he joined his friends.
TAKE ONE'S NAME IN VAIN
Meaning of TAKE ONE'S NAME IN VAIN in English
American idioms English vocabulary. Английский словарь американских идиом. 2012