Pronunciation: (poosh'ur),[key] —n. 1. a person or thing that pushes.
2. Slang.a peddler of illegal drugs.
3. Aeron.an airplane that is driven by pusher propellers.
4. Naut.one of the masts abaft the mizzen on a sailing vessel having more than three masts, either the sixth or seventh from forward. Cf. driver (def. 10b), spanker (def. 1b).
5. Railroads.a helper attached to the rear of a train, usually to provide extra power for climbing a steep grade.