What's the meaning of "bitching" in the following sentence taken from references in 'tfd.com'?
December: I quit bitching with grateful thanks for all the good times, things and friends God has provided me with this year.
I think in this context, they mean "complaining", but it looks like there are other errors in the source sentence so it's not completely clear what they meant.
Basically, it's a somewhat crude synonym for "bellyaching," which is a colloquial term for "complaining," as the previous answerer says.
However, when used as an adjective, it's a somewhat crude synonym for "cool," which is a colloquial term for "admirable," "attractive," or "desirable"-- as in the the lyrics to the Dead Milkmen's song "Bitchin' Camaro" (1985):
Bitchin' Camaro, bitchin' Camaro/ I ran over my neighbors/ Bitchin' Camaro, bitchin' Camaro/ Now it's in all the papers
I recall a much older instance of the adjective use of "bitching" in the Dead Milkmen sense--from Jim Brosnan's 1962 book Pennant Race, where he quotes Pittsburgh Pirates first baseman Dick Stuart as saying [inexact quote here because I don't have the book with me, but I'll try to remember to look it up when I get home], "I add 15 points to my batting average just knowing I look bitching up there [at the plate]."
The literal meaning of "bitching" is to "act like a bitch."
The figurative meaning is to complain. The "bitch" is a complainer or nagger, by implication (though not necessarily) a woman.