1. gastroenterologist a physician who specializes in diseases of the gastrointestinal tract
  2. numerologist a believer in numerology
  3. cosmetologist an expert in the use of cosmetics
  4. responsibility the social force that binds you to a course of action
  5. craniologist someone who claims to be able to read your character from the shape of your skull
  6. gerontologist a specialist in gerontology
  7. criminologist a specialist in criminology
  8. cryptologist someone skilled in devising, analyzing, or deciphering codes
  9. cosmologist an astronomer who studies the evolution of the universe
  10. graphologist a specialist in inferring character from handwriting
  11. gynecologist a specialist in gynecology
  12. rheumatologist a physician specializing in rheumatic diseases
  13. gynaecologist a specialist in gynecology
  14. speleologist a person who explores caves
  15. astrologist someone who predicts the future by the positions of the planets and sun and Moon
  16. ornithologist a scientist who studies birds
  17. spelaeologist a person who explores caves
  18. serologist a medical scientist who specializes in serology
  19. epidemiologist a specialist who studies the spread and control of diseases
  20. herpetologist a scientist who studies reptiles and amphibians