1. back matter written matter following the main text of a book
  2. backstairs a second staircase at the rear of a building
  3. backwater a body of water that was created by a flood or tide
  4. picometer a metric unit of length equal to one trillionth of a meter
  5. bacterise subject to the action of bacteria
  6. backbiter one who attacks the reputation of another by slander or libel
  7. backhander a backhanded blow
  8. backscatter scatter by the atoms of the medium through which it passes
  9. Cape Hatteras a promontory on Hatteras Island off the Atlantic coast of North Carolina
  10. picometre a metric unit of length equal to one trillionth of a meter
  11. bacterize subject to the action of bacteria
  12. tachometer measuring instrument for indicating speed of rotation
  13. air mattress a mattress that can be stored flat and inflated for use
  14. tachymeter a theodolite designed for rapid measurements
  15. book matches a paper match that strikes only on a specially prepared surface
  16. balusters a railing at the side of a staircase or balcony to prevent people from falling
  17. machmeter speedometer for measuring the speed of an aircraft relative to the speed of sound
  18. backstair secret and sly or sordid
  19. Clamatores used in some classification systems
  20. bitters alcoholic liquor flavored with bitter herbs and roots