I don't know, and I have no reason to care. But one of the more bizarre political stories of 2010 has been the series of Republican political operatives claiming to have had sexual relations with Nikki Haley, the leading Republican candidate for governor in South Carolina. (Haley denies the claims, and blames her political rivals for concocting the stories.)
I bring this up only because it's necessary background for a discussion of the second sex-related linguistic innovation to come out of South Carolina politics in the past year. The first, of course, was "hiking the Appalachian trail", which was one of the cover stories that the current S.C. governor, Mark Sanford, offered for a trip to Argentina to visit his mistress.
One of the first sites to flag that expression as an idiom-in-the-making was Talking Points Memo. And in a recent post at TPM on the Nikki Haley story, Josh Marshall implicitly noted a gap in the word-stock of English, and proposed a way to fill it ("Somethin' in the Water Down There", TPM 6/2/2010):
I'm not sure which would make for a more colorful and entertaining story: Haley exposed as an inveterate … what I guess you'd call, man-izer or the idea that a series of different GOP operatives, each of whom is currently married, conspiring to publicly allege phony affairs with Haley. What say you?
As Josh's pause-signalling dots suggest, there's a lexical lacuna here. A male politician who is prone to out-of-wedlock hookups would be called a womanizer, but there seems to be no appropriate equivalent for a female. The term slut, for example, has connotations that are entirely inappropriate for a case of this kind. So Josh's attempt to coin manizer is an entirely rational move, though I'm not sure it will catch on.
According to the OED, womanize originally meant "To make a woman of (a man); gen. to render effeminate, to emasculate", or intransitively "To become womanlike; to behave like a woman". The meaning "To consort illicitly with women" didn't arise until the late 19th century, when the "go wenching" sense of womanize developed as an instance of the OED's pattern 1.b. for -ize, "the intrans. sense 'to act some person or character, do or follow some practice'" associated with the root, e.g. agonize, apologize, apostatize, botanize, dogmatize, geologize, philosophize, syllogize, sympathize, theorize.
Thus to botanize is to go around "following some practice" associated with botany ("doing botany") and to womanize is to go around "following some practice" associated with women ("doing women"). This coinage worked in Victorian or Edwardian England (because why else would a man pay attention to women taken as a group?), and once established, it persisted as a useful term for a common concept.
Manize is a bit more problematic, I think. This is partly because of the nature of the stem: -ize, originally Greek, has learned to attach to native words (bastardize, mesmerize, mercerize, bowdlerize, womanize) but as far as I know, all of the reasonably-common roots of -ize words are two or more syllables long. There may also be some issues associated with man as the pragmatically unmarked category of human — "following some practice associated with men" may not connect quickly enough to sex.
But as powerful women become more and more common, we'll need some word for the inveterate … um, manizers among them, and I'll be rooting for Josh's coinage.
[Update -- Silvia Killingsworth notes that
Anthony Lane [independently?] coined the term last week when he wrote his Cinema review of the new Michael Douglas film, “Solitary Man”:
He and Douglas put their scenes together with no more ado than someone making a sandwich, and they leave us with the wry thought that the people the womanizer really loves—the ones he can live with, and die with—are guys. He’s a manizer, and he never even knew it.
That's the same word but not quite the same sense, it seems to me. Still, perhaps it's more evidence that manizer is a coinage whose time has come. (And I guess I should note that the Urban Dictionary has had entries for this coinage since 2004 or so.]