-ist

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

pyrotechnist
1. Someone who is employed, or skilled, in pyrotechny.
2. A maker or displayer of fireworks.
quadrigamist
Someone who has married four times and as a result, has four spouses; such as, four wives or four husbands at the same time.
quamtophilist
A collector of novelties.
querist (s) (noun), querists (pl)
Someone who is looking for information: Eric, the querist, was a reporter who wanted to find out what people think about the government's new health plan.
queryist (s) (noun), queryists (pl)
A person who probes for information and seeks to fulfill an objective: Mrs. Jameson, being a queryist, was making an effort to determine why there were so many objections to the new head of government after she had received so many votes from the people during the election.
queselcardophilist, queselcardophile
A collector of radio-ham cards.
quietist
radiobiologist
An expert in radiobiology or the branch of science concerned with effects of light and of ultraviolet and ionizing radiations on living tissues or organisms.
radiodontist
radiologist
radiotherapist
rapist (s) (noun), rapists (pl)
Someone who forces another person to have sexual intercourse: The serial rapist was caught by the police and confined to jail until a court appearance.

The newspapers reported on a gang of rapists who were terrorizing the city.

rapturist (s) (noun), rapturists (pl)
A person who believes he or she will be transported into the spiritual realm, sometimes applied to the second coming of Jesus Christ, when true believers are expected to rise up to join Him in heaven: In an unprecedented action, the rapturists sold all of their worldly belongings and gathered at the river with joyful expressions on their faces in anticipation of meeting their Lord.
rationalist
razrapophilist
A collector of razor-blade packets.