Etymology: < classical Latin ad- (prefix) < ad (preposition) to < the same Indo-European base as at prep.Uses in Latin. In classical Latin ad- is usually combined with verbs or verbal derivatives, and adds one or more of the senses of the preposition, e.g. motion to or against (e.g. adīre (see adient adj.), aggredī : see aggress v.) or to oneself (e.g. accipere accept v.), direction towards (e.g. advertere advert v.), placing on or against (e.g. acclīnāre accline v., alligāre alligate v.), reaching (e.g. advenīre advene v., attingere attain v.), nearness or presence (e.g. adesse (see adessive adj.), alluere : see alluvion n.), attention, response (e.g. admīrārī admire v., adnuere annuate v.), adjustment (e.g. adaptāre adapt v., assuēscere : see assuete adj.), inception (e.g. adedere (see adesed adj.), adūrere adure v.), intensification (e.g. adamāre adamate v., and also the adverbs apprīmē extremely, affabrē ingeniously). Formal variation in Latin. Before the consonants c , f , g , l , n , p , q , r , s , t , ad- was often assimilated in Latin, as ac- , af- , ag- , al- , an , ap- , ac- , ar- , as- , at- (compare e.g. classical Latin alleviāre alleviate v., attenuāre attenuate v., post-classical Latin accurtare : see accurtation n.); compare similar assimilation before b in post-classical Latin abbreviare , for *adbreviare (see abbreviate v.). Before sc , sp , st it was reduced to a- (in e.g. ascendere ascend v., aspīrāre aspire v., astrictus astrict adj.). It remained before vowels, and the consonants d , h , consonantal i , m , and consonantal u . Development in Old French. The regular development in Old French was to a- , even before another vowel (which was hence in hiatus), thus classical Latin adōrāre > Old French aorer (see adore v.), classical Latin adornāre > Old French aorner (see adorn v.), classical Latin adaestimāre > Old French aesmier . Classicizing influence in French and English. From early in the documented history of Old French, but with increasing frequency in Middle French, forms are found which show remodelling under classicizing influence, e.g. adorer , adorner . Some cases are purely graphic, as annoncer beside anoncer (see announce v.), allouer beside alouer (see allow v.), attendre beside atendre (see attend v. 1), aggregier beside agregier (see aggrege v.). This variation in form and spelling is reflected also in French borrowings in Middle English. In later Middle English and especially in early modern English this classicizing trend was often carried further than in French, and in some cases classicizing forms were found which are not paralleled in French, while in others the classicizing form was ultimately selected as the standard form in modern English but not in French (compare French adresser beside English address v., French avertissement beside English advertisement n.). Words subsequently formed in French and adopted in English, or formed in English either after Latin words or independently, follow the Latin forms of the prefix. Formations within English. Formations within English after Latin models are found from the early 16th cent., e.g. admix v., adnumber v. Entirely new formations within English, which cannot be interpreted as showing remodelling or adaptation of other words in English or in other languages, are very rare. Analogical alteration of words not etymologically showing this prefix. In many cases spellings in ad- (and likewise ac- , ag- , al- , an- , etc.) were extended analogically (in English or French or in both) to words which do not show this prefix etymologically, e.g. advance v. (in this case affecting also the pronunciation), addebted adj., affray v., afforce v., allay v.1, ally v. (see also examples at ac- prefix); compare also the complex form history of admiral n. Compare also the spellings of some newly coined words such as addeem v. and addoom v.
This entry has been updated (OED Third Edition, December 2011; most recently modified version published online March 2021).
prefix