1. a1 - Noun
2. a1 - Adjective
first rate or excellent
(of a ship) in first class condition
(informal) In good health.
(informal) In excellent or top condition.
(of a ship) First-class. (Compare A 2 and A 3, which are inferior grades.)
A1 (plural A1s)
Under the International Union of Railways ("UIC") classification system, a steam locomotive that has two coupled driving wheels followed by two trailing wheels, with no leading wheels; also called an 0-2-2.
A1 (plural A1s)
Under the International Union of Railways ("UIC") classification system, a steam locomotive that has two coupled driving wheels followed by two trailing wheels, with no leading wheels; also called an 0-2-2.