A one

[ ey wuhn ]
/ ˈeɪ ˈwʌn /
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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 a-1

Word Origin and History for a-1

A-1


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).

Online Etymology Dictionary, © 2010 Douglas Harper