ad hominem

word-forming element expressing direction toward or in addition to, from Latin ad "to, toward" in space or time; "with regard to, in relation to," as a prefix, sometimes merely emphatic, from PIE root *ad- "to, near, at."

Simplified to a- before sc-, sp- and st-; modified to ac- before many consonants and then re-spelled af-, ag-, al-, etc., in conformity with the following consonant (as in affection, aggression). Also compare ap- (1).

In Old French, reduced to a- in all cases (an evolution already underway in Merovingian Latin), but French refashioned its written forms on the Latin model in 14c., and English did likewise 15c. in words it had picked up from Old French. In many cases pronunciation followed the shift.

Over-correction at the end of the Middle Ages in French and then English "restored" the -d- or a doubled consonant to some words that never had it (accursed, afford). The process went further in England than in France (where the vernacular sometimes resisted the pedantic), resulting in English adjourn, advance, address, advertisement (Modern French ajourner, avancer, adresser, avertissement). In modern word-formation sometimes ad- and ab- are regarded as opposites, but this was not in classical Latin.

"tiny human being produced artificially," 1650s, from Latin homunculus (plural homunculi), literally "little person," with -culus, diminutive suffix, + homo (genitive hominis), which technically meant "male human," but it also was used with a sense "the human race, mankind;" while in Vulgar Latin it could be used as "one, anyone, they, people" and in logical and scholastic writing as "a human being, person."

This is conjectured to be from PIE *(dh)ghomon- (source also of Old Irish duine, Welsh dyn, Breton den "man;" Old Prussian smunents, smunets "man;" Old Lithuanian žmuo "person," Lithuanian žmogus "man," žmones "people," Gothic guma, Old High German gomo, Old Norse gume, Old English guma "man"). The literal sense is "earthling," from PIE root *dhghem- "earth" (compare human (adj.)). Other Latin diminutives from homo included homullus, homuncio.