1. Thickening of tissue in the motor tracts of the lateral columns and anterior horns of the spinal cord.
4. (slang) A gangster's pistol.
7. The event of something ending.
11. Resinlike substance secreted by certain lac insects.
12. A transuranic element.
13. Predatory black-and-white toothed whale with large dorsal fin.
14. A vinyl polymer used especially in paints or adhesives.
15. The state of needing something that is absent or unavailable.
16. (computer science) A coding system that incorporates extra parity bits in order to detect errors.
17. The capital and largest city of Yemen.
20. Title for a civil or military leader (especially in Turkey).
22. Avatar of Vishnu.
23. A mark left by the healing of injured tissue.
26. A crystalline rock that can be cut and polished for jewelry.
27. Having undesirable or negative qualities.
30. The elementary stages of any subject (usually plural).
32. A Chadic language spoken south of Lake Chad.
39. A radioactive element of the actinide series.
41. A flat wing-shaped process or winglike part of an organism.
42. Ancient Hebrew unit of liquid measure = 1.5 gallons.
45. A digital display that uses liquid crystal cells that change reflectivity in an applied electric field.
46. A condition (mostly in boys) characterized by behavioral and learning disorders.
47. The basic unit of money in Iran.
48. A plant hormone promoting elongation of stems and roots.

1. A large mountain system in south-central Europe.
2. Rock that in its molten form (as magma) issues from volcanos.
3. The act of scanning.
4. A Russian prison camp for political prisoners.
5. (Irish) Mother of the ancient Irish gods.
6. Psychoactive substance present in marijuana.
7. Conforming to truth.
8. An evergreen tree of the family Ulmaceae that grows in tropical America and Africa and Asia.
9. English scholastic philosopher and assumed author of Occam's Razor (1285-1349).
10. A civil or military authority in Turkey or Egypt.
18. A river in north central Switzerland that runs northeast into the Rhine.
19. A large fleet.
21. Title for a civil or military leader (especially in Turkey).
24. A white metallic element that burns with a brilliant light.
25. A public promotion of some product or service.
28. The blood group whose red cells carry both the A and B antigens.
29. A soft silvery metallic element of the alkali earth group.
31. A periodic paperback publication.
33. Harsh or corrosive in tone.
34. A city in northern India.
35. Any of numerous local fertility and nature deities worshipped by ancient Semitic peoples.
36. Surrealist Spanish painter (1904-1989).
37. Type genus of the Alcidae comprising solely the razorbill.
38. A quantity of no importance.
40. Being one more than two.
43. A yellow trivalent metallic element of the rare earth group.
44. A trivalent metallic element of the rare earth group.