I. ə-ˈbȯrd adverb or adjective
Date: 14th century
1. : alongside
2.
a. : on, onto, or within a vehicle (as a car or ship)
b. : in or into a group, association, or organization
her second promotion since coming aboard
3. baseball : on base
II. preposition
Date: 15th century
: on , onto , within
go aboard ship
aboard a plane