1. particle detector a chamber in which particles can be made visible
  2. articulate express or state clearly
  3. art director the director in charge of the artistic features of a theatrical production (costumes and scenery and lighting)
  4. board of directors a group of persons chosen to govern the affairs of a corporation or other large institution
  5. articulatio radiocarpea a joint between the distal end of the radius and the proximal row of carpal bones
  6. article of commerce an article that is offered for sale
  7. water-cooled reactor nuclear reactor using water as a coolant
  8. articulatio coxae the ball-and-socket joint between the head of the femur and the acetabulum
  9. articulatio trochoidea a freely moving joint in which movement is limited to rotation
  10. stage director someone who supervises the actors and directs the action in the production of a stage show
  11. Carthamus tinctorius thistlelike Eurasian plant widely grown for its red or orange flower heads and seeds that yield a valuable oil
  12. article of furniture furnishings that make a room or other area ready for occupancy
  13. arteriectasis an abnormal distension of an artery
  14. articulatio genus hinge joint in the human leg connecting the tibia and fibula with the femur and protected in front by the patella
  15. Northwest Territories a large territory in northwestern Canada
  16. articulatio talocruralis a gliding joint between the distal ends of the tibia and fibula and the proximal end of the talus
  17. arteriectasia an abnormal distension of an artery
  18. music director the person who leads a musical group
  19. articulated ladder a ladder consisting of segments (usually four) that are held together by joints that can lock in place
  20. angina pectoris a heart condition marked by paroxysms of chest pain due to reduced oxygen to the heart