Etymology: < classical Latin -ārius, -ārium. The regular phonetic representation of these in Old French was -air , but most of the words that actually lived on into Old French had -ier (apparently by confusion with words in -iārium or -erium , of which -ier was the regular representation), in Anglo-Norman -er , examples of which still remain in English primer n.¹, danger n., antiphoner n., and names of trades and offices, like carpenter n., usher n. (compare -er suffix²), while others, as bursar n., calendar n., mortar n.¹, vicar n., have recently been remodelled with -ar suffix² after Latin. But in words of later learned adaptation in French, Latin -ārius , -ārium were represented by French -aire ; in Anglo-Norman -arie and Middle English -arie , later -arye , now -ary , as in classical Latin contrārius , French contraire , English contrarie , contrarye , now contrary adj.; and this is the regular form in which Latin words in -ārius, -arium, or their French representatives in -aire are now adapted in English, and on which new analogical formations are modelled.

Etymology: < classical Latin -āris (stem -āri- ) of the kind of, belonging to (see -ar suffix¹).In classical Latin several words had forms both in -āris and -ārius ; and in later French words of literary introduction, both these Latin endings are levelled under -aire , e.g. classical Latin contrārius , mīlitāris , French contraire , militaire . So, in the same way that French -aire from -ārius gives -ary in English, French -aire from -āris has occasionally also been adapted as -ary instead of the more regular -ar ; e.g. capillary adj., exemplary adj., maxillary adj., military adj., salutary adj.