Oscar — NATO Phonetic Alphabet for O

Oscar is a common personal name in English, and today it's just as likely to conjure the Academy Awards statuette — neither association had anything to do with why ICAO chose the word for the letter O.

Its maritime signal flag carries a genuinely serious, still-active meaning when hoisted alone: "man overboard." It's one of the few flags in the entire system where the signal isn't just informational or procedural — it's a real emergency alert that a vessel is missing someone in the water, and it remains an actively taught and used maritime safety signal today, not a historical curiosity.

The word has a naval life of its own beyond flags and spelling, too: NATO's reporting names for Soviet and Russian submarine classes reuse this same 26-word alphabet, and the Oscar-class, a large Cold War-era cruise-missile submarine design, is named directly after this letter. That's a considerably heavier association than the word's ordinary use as a first name ever suggests on its own.