Noun
a homing pigeon used to carry messages
Source: WordNetcarrier-pigeon
Compare sending someone a text message and getting a love letter delivered by carrier pigeon. No contest. Bryan Callen
When the Rothchilds got the word about the battle of Waterloo - in the movie it was by carrier pigeon - they didn't rush down and buy British consols, the government bonds. They rushed in and sold, and then, in the panic, they bought. George Goodman