We don't have synonyms for knifeboard yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are kneeboard.
(n) :
A board on which knives are cleaned or polished.
(n) :
(historical, chiefly attributive) A way of arranging benches back to back, resembling a knifeboard; common on the open upper deck of early double-deck omnibuses and trams.
(n) :
(historical, by extension) An early bus with narrow, restrictive seating; a knifeboard bus.
(n) :
A board on which knives are cleaned or polished.
(n) :
(historical, chiefly attributive) A way of arranging benches back to back, resembling a knifeboard; common on the open upper deck of early double-deck omnibuses and trams.
(n) :
(historical, by extension) An early bus with narrow, restrictive seating; a knifeboard bus.