by God

Ellipsis of a full oath of the form "I swear by God that…"

by God (not comparable)

1. Used as an oath to emphasize the veracity of an associated statement.
   • 1814 May 9, [Jane Austen], chapter VII, in Mansfield Park: […], volume III, London: […] [George Sidney] for T[homas] Egerton, […], →OCLC, page 150:

     I should not wonder if you had your orders to-morrow; but you cannot sail with this wind, if you are to cruize to the westward; Captain Walsh thinks you will certainly have a cruize to the westward, with the Elephant. By G⁠—, I wish you may.

   • 2007, Cassandra King, Queen of Broken Hearts:

     With a frown, Rye studies my face. He disengages my arm in order to take my hand in both of his and squeeze it tight. "Why don't you go back and confront him, sweetheart? I'll go with you, by God. I don't like the idea of him bullying you, and he needs to hear that."

2. Used as an intensifier.
   • 1991 November 20, Paul Hendrickson, “Echoes Of the Day of Infamy”, in Washington Post:

     I saw that map and I said right then, 'Someday I'm going to make a map of how it was that day, make a drawing of Pearl Harbor, and I'll make it right.' And I did, by God.

by God (not comparable)

1. (informal, mildly blasphemous) Genuine, actual.
   • 1973, Cormac McCarthy, Child of God, page 81:

     I’ll tell you one thing he was if he wasn’t no soldier. He was a by god White Cap.

   • 1995, Benjamin Bradlee, A Good Life, page 198:

     Fleeson was known as “God’s angry woman,” and she called herself a “by God practicing liberal.”

by God

1. An exclamation of surprise.

   By God! That chicken has no head!

   • 1822 May 29, [Walter Scott], chapter III, in The Fortunes of Nigel. […], volume III, Edinburgh: […] [James Ballantyne and Co.] for Archibald Constable and Co.; London: Hurst, Robinson, and Co., →OCLC, page 85:

     […] having made a cross cut, so as to ascertain the depth of the fat upon the chest, exclaimed, in a sort of rapture, “Three inches of white fat on the brisket!—prime—prime, as I am a crowded sinner—and de’il ane o’ the lazy loons in but mysell! Seven—aught—aught tines on the antlers. By G⁠—⁠d, a hart of aught tines, and the first of the season! […]”

• See Thesaurus:wow

• Godby