(1) One who studies the theory that blood cells have two origins, from the lymphatic system and from the bone marrow.
(2) One who holds the view in psychology that the mind and body function separately, without interchange.
(3) One who believes in the existence of two entities (as one good and one evil); ditheism
(2) Psychological bitheists provide a good insight, psychologically.
(3) I identify myself as a bitheist, for the idea of two opposite forces, one male and evil and the other good and female, or vice versa, makes a lot of sense and helps explain the neutrality of our universe.