preboard

verb

1. (transitive)To (allow to) step or climb onto or otherwise enter a ship, aircraft, train or other conveyance before other people are allowed to board.

   “People requiring assistance or extra time will be preboarded.”

   “Airlines must permit some parents — or passengers with food allergies themselves — to preboard in order to wipe down seats, federal regulators said. […] All customers with peanut and tree nut allergies are now allowed to preboard and wipe down surfaces, according to an airline spokeswoman.”

2. (transitive)To set the shape of (a garment, especially a stocking) by heating on a form or board before dyeing.