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ad-(3) (iou)



ad- prefix.
Repr. Latin ad preposition 'to', with sense of motion to or direction towards, addition, adherence, increase. The d was assim. to following c, f, g, l, n, p, q, r, s, t (see AC-, AF-, etc.); ad- was reduced to a- before sc, sp, st (see A-8). In Old French the double consonant of acc-, add-, etc., were reduced to single ones, and adv- became av-, and Old French words were adopted with such forms in English; but in 14 these began to be refash. after Latin, as address. Opp. to ab- away from, as in adaxial, abaxial, ad- is recent.
At the same time ad- was substituted for a- of different origin, as in advance, addebted, admiral.