A one[ā′ wun′]
A one definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
A one definition by American Heritage Dictionary
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
also A-1adjective Informal
Origin: From classification for ships in The Lloyd's Register of Shipping.
a one - Phrases/Idioms
Also, A-1; A-number-one. First-class, of the best quality, as in This is an A-one steak. The term comes from Lloyd's, the British insurance company, which in its 1775 shipping register designated the condition of a ship's hull by a letter grade (A, B, etc.) and of its cables, anchor, and other equipment by a number grade (1, 2, etc.). By the early 1800s A-1, the best possible grade, was being transferred to anything of superior quality.