1. ad nauseam to a sickening or excessive extent
  2. autonomy political independence
  3. communism a theory favoring collectivism in a classless society
  4. addendum textual matter that is appended to the end of a publication
  5. adynamia lack of strength or vigor (especially from illness)
  6. Adenium one species: succulent shrub or tree of tropical Africa and Arabia
  7. atonalism the absence of a key; alternative to the diatonic system
  8. hedonism an ethical system that values the pursuit of pleasure
  9. adenosine a nucleoside that is a structural component of nucleic acids
  10. adonis a handsome young man
  11. ethnicity an affiliation resulting from racial or cultural ties
  12. adenoma a benign epithelial tumor of glandular origin
  13. adenosis a disorder of the glands of the body
  14. adamant very hard native crystalline carbon valued as a gem
  15. idealism belief that the best possible concepts should be pursued
  16. Arianism heretical doctrine taught by Arius that asserted the radical primacy of the Father over the Son
  17. autonomous existing as an independent entity
  18. Adansonia baobab; cream-of-tartar tree
  19. Adonis a handsome youth loved by both Aphrodite and Persephone
  20. Aidoneus the god of the underworld in ancient mythology