I had to look this one up, and thought some of you may be interested in the usage note:
ad hom·i·nem (hŏm'ə-nĕm', -nəm)
adj.
Appealing to personal considerations rather than to logic or reason: Debaters should avoid ad hominem arguments that question their opponents' motives.
[Latin : ad, to + hominem, accusative of homō, man.]
ad hom'i·nem' adv.
USAGE NOTE As the principal meaning of the preposition ad suggests, the homo of ad hominem was originally the person to whom an argument was addressed, not its subject. The phrase denoted an argument designed to appeal to the listener's emotions rather than to reason, as in the sentence The Republicans' evocation of pity for the small farmer struggling to maintain his property is a purely ad hominem argument for reducing inheritance taxes. This usage appears to be waning; only 37 percent of the Usage Panel finds this sentence acceptable. The phrase now chiefly describes an argument based on the failings of an adversary rather than on the merits of the case: Ad hominem attacks on one's opponent are a tried-and-true strategy for people who have a case that is weak. Ninety percent of the Panel finds this sentence acceptable. The expression now also has a looser use in referring to any personal attack, whether or not it is part of an argument, as in It isn't in the best interests of the nation for the press to attack him in this personal, ad hominem way. This use is acceptable to 65 percent of the Panel.•Ad hominem has also recently acquired a use as a noun denoting personal attacks, as in “Notwithstanding all the ad hominem, Gingrich insists that he and Panetta can work together” (Washington Post). This usage may raise some eyebrows, though it appears to be gaining ground in journalistic style.•A modern coinage patterned on ad hominem is ad feminam, as in “Its treatment of Nabokov and its ad feminam attack on his wife Vera often border on character assassination” (Simon Karlinsky). Though some would argue that this neologism is unnecessary because the Latin word homo refers to humans generically, rather than to the male sex, in some contexts ad feminam has a more specific meaning than ad hominem, being used to describe attacks on women as women or because they are women, as in “Their recourse … to ad feminam attacks evidences the chilly climate for women's leadership on campus” (Donna M. Riley).
From Gurunet. [/showing my ignorance yet again]
