1. to board (an aircraft, ship, or other vehicle) before the general boarding period or before other passengers
Usage: transitive or intransitive; common in air travel

Examples

• Passengers with young children were allowed to preboard the flight.
• First-class ticket holders can preboard before economy passengers.
• We preboarded the cruise ship an hour before the official boarding time.
• Elderly passengers and those needing assistance may preboard.
• The airline announced that frequent flyers could preboard at gate 12.