A1

Meaning

Adj

1. (informal) In good health.
2. (informal) In excellent or top condition.
3. First-class. (Compare A 2 and A 3, which are inferior grades.)

Noun

Under the International Union of Railways (French: Union internationale des chemins de fer, 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.

Synonyms

best

first-class

most

first-rank

Etymology

From various rating systems, as that of Lloyd's of London or the condition of insured ships. First attested in 1837.