1. nitrate bacterium any of the nitrobacteria that oxidize nitrites into nitrates
  2. nitrite bacterium any of the nitrobacteria that oxidize ammonia into nitrites
  3. dirty trick an unkind or aggressive trick
  4. dirty story an indelicate joke
  5. dart thrower a device resembling a sling that is used in various primitive societies to propel a dart or spear
  6. dry battery a voltaic battery consisting of two or more dry cells
  7. dirt track a racetrack that is not paved
  8. thirty-three being three more than thirty
  9. dictyopteran of or relating to or belonging to the order Dictyoptera
  10. dart board a circular board of wood or cork used as the target in the game of darts
  11. Dictyoptera in some classifications replaced by the orders (here suborders) Blattodea (cockroaches) and Manteodea (mantids); in former classifications often subsumed under a much broader order Orthoptera
  12. bathroom a room (as in a residence) containing a bathtub or shower and usually a washbasin and toilet
  13. dirty bomb an atom bomb that leaves considerable radioactive contamination
  14. dirty pool conduct that is unfair or unethical or unsportsmanlike
  15. thirty-third the ordinal number of thirty-three in counting order
  16. dirty war an offensive conducted by secret police or the military of a regime against revolutionary and terrorist insurgents and marked by the use of kidnapping and torture and murder with civilians often being the victims
  17. orthopteron any of various insects having leathery forewings and membranous hind wings and chewing mouthparts
  18. dart player someone who plays the game of darts
  19. master bedroom the principal bedroom in a house
  20. dartboard a circular board of wood or cork used as the target in the game of darts