What does Sey stand for?

Seychelles (MILB)

Air Seychelles - ICAO designator (FAAC)

Block Island, RI - Location identifier - FAA (FAAL)

Secondary Electron Yield

Secoya - Language symbol (ETLW)

Secretary - Telegraphy (PCTE)

Selibaby - Mauritania - Airport symbol (OAG)

Seymchan - Former USSR - Seismograph station code, US Geological Survey (SEIS)

Southeastern Yiddish (BJA)

Starlight Energy - Vancouver Stock Exchange symbol

Summer Employment Youth - DoD