A one

Also A-one,

[ey wuhn]

adjective

1. noting a vessel regarded by a shipping-classification society as being equipped to the highest standard and with equipment maintained in first-class condition.

2. Informal.,  Also A number one. first-class; excellent; superior.

   The meals there are A one.

Word History and Origins

Origin of A-one¹

First recorded in 1830–40

Idioms and Phrases

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.