We don't have synonyms for preboard yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are plyboard, pre-board and reboard.
(v) :
(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.
(v) :
(transitive, textiles) To set the shape of (a garment, especially a stocking) by heating on a form or board before dyeing.
(v) :
(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.
(v) :
(transitive, textiles) To set the shape of (a garment, especially a stocking) by heating on a form or board before dyeing.