1. Abney level a surveying instrument consisting of a spirit level and a sighting tube; used to measure the angle of inclination of a line from the observer to the target
  2. Aaron Burr United States politician who served as vice president under Jefferson; he mortally wounded his political rival Alexander Hamilton in a duel and fled south (1756-1836)
  3. Abel Tasman Dutch navigator who was the first European to discover Tasmania and New Zealand (1603-1659)
  4. 401-k plan a retirement savings plan that is funded by employee contributions and (often) matching contributions from the employer; contributions are made from your salary before taxes and the funds grow tax-free until they are withdrawn, at which point they can be converted into an IRA; funds can be transferred if you change employers and you can (to some extent) manage the investments yourself
  5. Aaron Copland United States composer who developed a distinctly American music (1900-1990)
  6. A. A. Milne English writer of stories for children (1882-1956)
  7. ABO system a classification system for the antigens of human blood
  8. A. E. Housman English poet (1859-1936)
  9. Abies fraseri small fast-growing but short-lived fir of southern Alleghenies similar to balsam fir but with very short leaves
  10. Abies grandis lofty fir of the Pacific coast of northwestern America having long curving branches and deep green leaves
  11. Abies lowiana medium to tall fir of central to western United States having a narrow erect crown and soft wood
  12. Abies venusta a pyramidal fir of southwestern California having spiny pointed leaves and cone scales with long spines
  13. Aare River a river in north central Switzerland that runs northeast into the Rhine
  14. Abies alba tall timber tree of central and southern Europe having a regular crown and grey bark
  15. 8 May 1945 the date of Allied victory in Europe, World War II
  16. ADP system a system of one or more computers and associated software with common storage
  17. 12-tone system a type of serial music introduced by Arnold Schoenberg
  18. 1st class mail that includes letters and postcards and packages sealed against inspection
  19. 440 yards a unit of length equal to a quarter of 1 mile
  20. 880 yards a unit of length equal to half of 1 mile