on board; on, in, or into a ship, train, airplane, bus, etc.

to step aboard.

alongside; to the side.

Baseball . 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.

all aboard! (as a warning to passengers entering or planning to enter a train, bus, boat, etc.

just before starting) Everyone get on!

adjective

not on , off

adjective

boarded , consigned , embarked , en route , in transit , loaded , on , on board , traveling , across , alongside , astride , athwart , on deck , present