Aboard
/əˈbɔːd/
adverb
On board; into or within a ship or boat; hence, into or within a railway car.
“We all climbed aboard.”
On or onto a horse, a camel, etc.
“To sling a saddle aboard.”
On base.
“He doubled with two men aboard, scoring them both.”
preposition
On board of; onto or into a ship, boat, train, plane.
“We all went aboard the ship.”
Onto a horse.
Across; athwart; alongside.