also A1, A-one, "first-rate," 1837 (in Dickens); a figurative use from Lloyd's of London marine insurance company's system for selective rating of merchant vessels ("Register of British and Foreign Shipping"), where it is the designation for ships in first-class condition. The letter refers to the condition of the hull of the ship itself, and the number rating to the equipment. Also used in equivalent ratings in U.S., where colloquially it is sometimes expanded to A No. 1 (which is attested by 1848 as top rating of entries in an agricultural fair).
also AA, abbreviation of Alcoholics Anonymous, attested by 1941, American English. The group name was the title of a book published in 1938 by the founder, Bill W. From 1914 as an abbreviation of anti-aircraft guns.
also aard-vark, South African groundhog, 1833 (in German from 1824), from Afrikaans Dutch aardvark, literally "earth-pig" (it burrows), from aard "earth," from Proto-Germanic *ertho- (see earth (n.)) + vark "pig," from Middle Dutch varken "small pig," which is from Proto-Germanic *farhaz (source also of Old High German farah, German Ferkel "young pig, sucking pig," a diminutive form; Old English fearh), from PIE root *porko- "young pig."