ad(n = noun.communication) advert, advertisement, advertising, advertizement, advertizing - a public promotion of some product or service;

   ad(r = adv.all) a.d., anno domini - in the Christian era; used before dates after the supposed year Christ was born; "in AD 200"

ad, abbr. (of a date) of the Christian era.

Usage:
Strictly, AD should precede a date (e.g. AD 410), but uses such as the tenth century AD are well established.

Etymology:
Anno Domini, 'in the year of the Lord'

ad, n. colloq. an advertisement.

Etymology:
abbr.

N  publication, public announcement, promulgation, propagation, proclamation, pronunziamento, circulation, indiction, edition, hue and cry, publicity, notoriety, currency, flagrancy, cry, bruit, hype, vox populi, report, the Press, public press, newspaper, journal, gazette, daily, telegraphy, publisher, imprint, circular, circular letter, manifesto, advertisement, ad, placard, bill, affiche, broadside, poster, notice, published, current, in circulation, public, notorious, flagrant, arrant, open, trumpet-tongued, encyclical, encyclic, promulgatory, exoteric, publicly, in open court, with open doors, Int, Oyez!, O yes!, notice!, notice is hereby given, this is to give, these are to give notice, nomina stultorum parietibus haerent, semel emissum volat irrevocabile verbum.