To speak impiously or profanely against; to blaspheme.

To speak impiously against, to rail profanely at (the deity, fate, destiny, etc.); to blaspheme.

transitive. To blaspheme against; to blame.

To swear by (a thing) falsely or profanely.

transitive. To speak irreverently of, utter impiety against (God or anything sacred.)

transitive. Scottish. To swear falsely by (a god); to take (a god's name) in vain. Obsolete.