A one

[ ey wuhn ]
/ ˈeɪ ˈwʌn /
|

adjective

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-one, A 1, A-1.

Origin of A one

First recorded in 1830–40
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for a1

British Dictionary definitions for a1

A1

A-1 or A-one

/ (ˈeɪˈwʌn) /

adjective

in good health; physically fit
informal first class; excellent
(of a vessel) with hull and equipment in first-class condition

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012