in figurative sense of "first-rate," 1837, in Dickens; from Lloyd's of London designation for ships in first-class condition (with the letter referring to the condition of the ship and the number to that of the stores).
mod. of the highest rating. : This steak is really A-1!
Dictionary of American Slang and Colloquial Expressions by Richard A. Spears.Fourth Edition. Copyright 2007. Published by McGraw-Hill Education.
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language Address 1 code. An a1 code interpreter, by Matthew Newhook email@example.com was used to test compiler output. It requires gcc 2.4.2 or higher and is portable to computers with memory segment protection. (ftp://ftp.cs.mun.ca/pub/a1). (1994-07-19)