Толковый словарь английского языка Oxford English Reference - ac

abbr. 1 (also ac) alternating current. 2 Brit. aircraftman. 3 before Christ. 4 Companion of the Order of Australia. Etymology: sense 3 f. L ante Christum AC symb. Chem. the element actinium. AC suffix forming adjectives which are often also (or only) used as nouns (cardiac; maniac) (see also -ACAL). Etymology: F -aque or L -acus or Gk -akos adj. suffix