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.
American Organization of Nurse Executives
abbreviation (in England, Wales, and Northern Ireland) Area of Outstanding Natural Beauty: an area designated by the appropriate government bodies as requiring protection to conserve and enhance its natural beauty
aoo American Oceanic Organization
aop aspect-oriented programming
aopa American Orthotic and Prosthetic Association