knifeboard

noun3

1. •
   A board on which knives are cleaned or polished.
2. •
   [before a noun] (historical) A way of arranging benches back to back, resembling a knifeboard; common on the open upper deck of early double-deck omnibuses and trams.

   • Arthur Smith, A Summer Idyll On 'busses' knifeboards stretch'd, / The City clerks all tongue-protruded lay.
3. •
   (historical) An early bus with narrow, restrictive seating; a knifeboard bus.