1. (Judaism) Sacred chest where the ancient Hebrews kept the two tablets containing the Ten Commandments.
4. An organization of countries formed in 1961 to agree on a common policy for the sale of petroleum.
8. The elementary stages of any subject (usually plural).
11. Two items of the same kind.
12. German organist and contrapuntist (1685-1750).
13. A close friend who accompanies his buddies in their activities.
14. An Arabic speaking person who lives in Arabia or North Africa.
16. A member of the Taracahitian people of central Mexico.
17. An Anatolian language.
19. Experiencing or showing sorrow or unhappiness.
20. (botany) Of or relating to the axil.
21. A member of a North American Indian people speaking one of the Hokan language.
23. One of the most common of the five major classes of immunoglobulins.
24. South African term for `boss'.
28. A nucleic acid consisting of large molecules shaped like a double helix.
30. (sports) The chief official (as in boxing or American football) who is expected to ensure fair play.
31. A federation of North American industrial unions that merged with the American Federation of Labor in 1955.
32. Large burrowing rodent of South and Central America.
35. A flat-bottomed volcanic crater that was formed by an explosion.
42. Type genus of the Alcidae comprising solely the razorbill.
44. A loose sleeveless outer garment made from aba cloth.
45. The longer of the two telegraphic signals used in Morse code.
47. Having leadership guidance.
48. The compass point midway between east and southeast.
49. Using speech rather than writing.
50. An agency of the United Nations affiliated with the World Bank.

1. (Babylonian) A demigod or first man.
2. Living in or characteristic of farming or country life.
3. Sluggish tailless Australian arboreal marsupial with gray furry ears and coat.
4. A Russian river.
5. An informal term for a father.
6. (computer science) A coding system that incorporates extra parity bits in order to detect errors.
7. A soft whitish calcite.
8. Type genus of the Apidae.
9. A Chadic language spoken south of Lake Chad.
10. Wearing or provided with clothing.
15. Capital city of the Apulia region on the Adriatic coast.
18. Green algae common in freshwater lakes of limestone districts.
22. The blood group whose red cells carry both the A and B antigens.
25. A radioactive element of the actinide series.
26. The branch of computer science that deal with writing computer programs that can solve problems creatively.
27. Conforming to truth.
29. Any member of Athapaskan tribes that migrated to the southwestern desert (from Arizona to Texas and south into Mexico).
33. A constellation in the southern hemisphere near Telescopium and Norma.
34. A soft silvery metallic element of the alkali earth group.
36. By bad luck.
37. Title for a civil or military leader (especially in Turkey).
38. Any of numerous local fertility and nature deities worshipped by ancient Semitic peoples.
39. Surrealist Spanish painter (1904-1989).
40. In bed.
41. A quantity of no importance.
43. A river in north central Switzerland that runs northeast into the Rhine.
46. A polyvalent metallic element that resembles chromium and tungsten in its properties.