Also found in: Wikipedia.
A mild oath, short for "I swear by God."
1. Used to emphasize or intensify one's statement. By God, I'm going to get to the bottom of this if it's the last thing I do! You're going to college, by God, and that's the last I want to hear about it!
2. Used to emphasize that something one is saying is true. A: "Tom, what happened to the money I gave you? I thought you were going to take it to the bank." B: "I did, by God! I handed it to the teller myself!" It was a pain in the rear end getting that old lawnmower working again, but by God I did it!
3. Used to emphasize an aspect or characteristic of someone or something. Used as a modifier before a noun; often hyphenated. I tell you, it's a by-God miracle no one was hurt in that accident! Tom is a by God hero—I won't let you talk that way about him!
4. An exclamation of shock or surprise. By God, you startled me! I didn't even hear you come in.
5. An exclamation of satisfaction or enjoyment. By God, that has to be one of the tastiest burgers I've had in years!
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.