Aboard

1. On board; into or within a ship or boat; hence, into or within a railway car. [First attested from around (1350 to 1470).]^[1]
2. On or onto a horse, a camel, etc. [First attested in the late 19^th century.]^[1]
3. (baseball) On base. [First attested in the mid 20^th century.]^[1]
4. Into a team, group, or company. [First attested in the mid 20^th century.]^[1]
5. (nautical) Alongside. [First attested from around (1350 to 1470).]