-ist

(Greek > Latin: a suffix; one who believes in; one who is engaged in; someone who does something)

proverbialist
Someone who originates, uses, or records proverbial sayings.
prudentialist
1. Someone who is governed by, or who acts from cautious motives when determining any action or line of conduct.
2. A reference to a person who is careful of the consequences of the actions that may result when he or she makes a decision to do something.
psammologist
psephologist
A political scientist who specializes in the study of elections; an electoral analyst or commentator.
psephomantist
Someone who uses stones or pebbles to divine or foretell the future.
pseudoantagonist
pseudologist
pseudomantist
psilanthropist (s) (noun), psilanthropists (pl)
Someone who believes that Jesus was not divine but merely a man: Psilanthropists generally deny both the virgin birth of Jesus and his deity or holiness.
psychiatrist
A physician who specializes in the study, treatment, and prevention of mental disorders.
psychologist
1. Someone who is trained in methods of psychological analysis, therapy, and research.
2. A specialist in psychology licensed to practice professional psychology (e.g., clinical psychologist), or qualified to teach psychology as a scholarly discipline (academic psychologist), or whose scientific specialty is a subfield of psychology (research psychologist).
psychopathist
An obsolete term for a psychiatrist.
psychopathologist
Someone who specializes in psychopathology.
psychophysiologist
Someone who studies psychophysiology.
psychosomaticist
A specialist in psychosomatic (mind and body) disorders.