1. On board; into or within a ship or boat; hence, into or within a railway car.
    We all climbed aboard.
  2. On or onto a horse, etc. <ref name=SOED/>
  3. On base. <ref name=SOED/>
    He doubled with two men aboard, scoring them both.
  4. Into a team, group, or company. <ref name=SOED/>
  5. Alongside. <ref name=SOED/>
    The ships came close aboard to pass messages.

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