- on board; on, in, or into a ship, train, airplane, bus, etc.: to step aboard.
- alongside; to the side.
- on base: a homer with two aboard.
- into a group as a new member: The office manager welcomed him aboard.
- on board of; on, in, or into: to come aboard a ship.
- (as a warning to passengers entering or planning to enter a train, bus, boat, etc., just before starting) Everyone get on!
- on, in, onto, or into (a ship, train, aircraft, etc)
- alongside (a vessel)
- a warning to passengers to board a vehicle, ship, etc
