To engage, enlist, or invest (as persons, money, etc.) in any affair.
To start, begin.
To cause to go on board a vessel or boat; to put on shipboard.
To get on a boat or ship or (outside the USA) an aeroplane.
To encarriage, to conjoin, to link; as in a series of entities, elements, objects or processes.
To suspend small particles in the current of a fluid.
To get into or board a railway train.
To put aboard a railway train.
To become trained or conditioned in a pattern of brain behavior.
To draw along as a current does.
To set up or propagate a signal, such as an oscillation.