1. apathy an absence of emotion or enthusiasm
  2. apropos of a suitable, fitting, or pertinent nature
  3. optics the branch of physics that studies the physical properties of light
  4. abattis a line of defense consisting of a barrier of felled or live trees with branches (sharpened or with barbed wire entwined) pointed toward the enemy
  5. abatis a line of defense consisting of a barrier of felled or live trees with branches (sharpened or with barbed wire entwined) pointed toward the enemy
  6. appetite a feeling of craving something
  7. appetence a feeling of craving something
  8. appetency a feeling of craving something
  9. apathetic showing little or no emotion or animation
  10. autopsy an examination and dissection of a dead body
  11. apotheosis model of excellence or perfection of a kind
  12. Apus apus common European bird with a shrieking call that nests chiefly about eaves of buildings or on cliffs
  13. aptness appropriateness for the occasion
  14. aptitude inherent ability
  15. appreciate be fully aware of; realize fully
  16. apterous (of insects) without wings
  17. uppityness assumption of airs beyond one's station
  18. Iapetus (Greek mythology) the Titan who was father of Atlas and Epimetheus and Prometheus in ancient mythology
  19. apodous (of snakes and eels) naturally footless
  20. Apodemus Old World field mice