Main definitions of OAO in English

: OAO1OAO2

OAO1

noun

military slang
  • One and only.

Origin

1920s; earliest use found in The New York Times.

Main definitions of OAO in English

: OAO1OAO2

OAO2

noun

  • Orbiting astronomical observatory.

Origin

1960s; earliest use found in Frederick Ira Ordway (b. 1927).