a·board [uh-bawrd, uh-bohrd]
1. on board; on, in, or into a ship, train, airplane, vehicle, etc.
- Come aboard the ship.
2. to the side.
3. Baseball. on base
4. into a group as a new member:
- The committee welcomed him aboard.
5. on board; on, in, or into
6. all aboard!, (as a warning to passengers entering or planning to enter a train, bus, boat, etc., just before leaving) Everyone get on!
1350-1400; Middle English abord (e) (see a-1, board ), perhaps conflated with Middle French a bord