1. useful having a helpful function
  2. unlawful not conforming to legality, moral law, or social convention
  3. fossil fuel energy-producing substance derived from preserved organisms
  4. soulful filled with or expressing deep emotion
  5. visual field all of the points of the physical environment that can be perceived by a stable eye at a given moment
  6. diesel fuel a heavy mineral oil used as fuel in diesel engines
  7. April fool a practical joke or trick played on the first day of April
  8. unlawfully not conforming to the law
  9. seal oil a pale yellow to red-brown fatty oil obtained from seal blubber; used in making soap and dressing leather and as a lubricant
  10. usually under normal conditions
  11. uselessly in a useless manner
  12. soulfully in a soulful manner
  13. usefully in a useful manner
  14. Asaph Hall United States astronomer who discovered Phobos and Deimos
  15. personal foul a foul that involves unnecessarily rough contact
  16. Yucca aloifolia a stiff yucca with a short trunk
  17. visual cell one of the cells of the retina that is sensitive to light
  18. skillful having or showing knowledge, ability, or aptitude
  19. usual occurring or encountered or experienced or observed frequently or in accordance with regular practice or procedure
  20. sulfur an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)