- noting a vessel regarded by a shipping-classification society as being equipped to the highest standard and with equipment maintained in first-class condition.
- Also A number one. Informal. first-class; excellent; superior: The meals there are A one.
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.