What is the correct spelling, dammit or damnit? And what is the difference?
Just writing this question brings up a red squiggly underneath damnit and the suggestions include dammit and damn it.
English Language & Usage Stack Exchange is a question and answer site for linguists, etymologists, and serious English language enthusiasts. It only takes a minute to sign up.
Sign up to join this communityWhat is the correct spelling, dammit or damnit? And what is the difference?
Just writing this question brings up a red squiggly underneath damnit and the suggestions include dammit and damn it.
The usage stats from the British National Corpus (BNC) look as follows:
ALL SPOKEN FICTION MAGAZINE NEWSPAPER ACADEMIC NON-ACAD MISC
dammit 125 3 99 3 8 0 7 5
damnit no results
damn it 158 12 137 1 1 0 2 5
And here are the stats from the Corpus of Contemporary American English (COCA):
ALL SPOKEN FICTION MAGAZINE NEWSPAPER ACADEMIC
dammit 763 20 647 60 30 6
damnit 94 2 86 6 0 0
damn it 1307 83 1112 58 36 18
The Corpus of Historical American English (COHA) paints the following picture:

(X axis: year, Y axis: incidences per million words)
Damnit could be used, though you're better off with "dammit" or "damn it". As per Wiktionary:
damnit
Nonstandard contraction of damn + it
Interjection (especially southern US)
Common misspelling of dammit.
Edit: As my answer points out, "damnit" is considered a misspelling of the more popular "dammit", which confirms ЯegDwight♦'s data.
dammit spellings to damnit. I corrected his correction.