-ist

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

gastrologist
gastronomist
gelatologist
A misspelling of gelotologist.
gelotologist (s) (noun), gelotologists (pl) (gelatologist is incorrect)
1. A laughter researcher.
2. Someone who specializes in gelotology, the study of humor, laughter, and the exercising of the gelastic muscles, a deeply serious exploration of what happens to the physical systems; such as, respiration and circulation, when people are exposed to humor.

Gelotologists are serious people who study laughter, and they would be the first to tell you that the results of their research is very much a laughing matter.

genealogist
geobiologist (s) (noun), geobiologists (pl)
An individual who studies the biosphere, or in the combination of geology and biology: A geobiologist specializes in the interdisciplinary field of scientific research that explores interactions between the biosphere, the lithosphere, and the atmosphere.
geobotanist (s) (noun), geobotanists (pl)
Someone who studies the geographic distribution of plants: Mr. Tree was a geobotanist who loved studying plants in comparison to their geological environments.
geochemist (s) (noun), geochemists (pl)
A geologist or chemist who is an expert in geochemistry: Dr. Evens was a geochemist who knew a lot about the chemical composition of the Earth and various planets.
geochronologist (s) (noun), geochronologists (pl)
Someone who studies the chronology, or time periods, of the Earth, as based on both absolute and relative methods of age determination: Jeff's mother was a geochronologist who studied and ascertained the ages of rocks, fossils, and sediments by scrutinizing the clues that were inherent in the samples themselves.
geologist (s) (noun), geologists (pl)
A scientist who specializes in the study of the origin, composition, history, structure, and processes of the Earth: Arthur's father was a geologist who was a professor in the geology department at the university.

One geologist claimed that geologists go to rock'n'roll concerts for entertainment, and when they relax, they rock in a rocking chair, but their favorite kind of transportation is a rocket.

geomantist (s) (noun), geomantists (pl)
Someone who foretells the future by using a system of divination by scattering pebbles, dust, sand grains, etc.: Sally's next-door neighbor was a geomantist who scattered seeds on the ground and interpreted their shapes and positions.
geomorphologist (s) (noun), geomorphologists (pl)
Someone who studies the surface configurations of the Earth and the history of geologic activities as represented by such surface features: Dr. Crawford was Tim's father who was a geomorphologist and did research on the origins of the geological aspects of the Earth.
geophagist (s) (noun), geophagists (pl)
Someone who consumes soil, clay, or earth: Little Sam wanted to eat some soil like the earthworms, which wasn't good for him, and he found out that such a person was termed a geophagist.

A geophagist is an individual who has a form of pica, or the indiscriminate craving for and consumption of substances, such as paint chips, clay, plaster, or dirt.

geophysicist (s) (noun), geophysicists (pl)
A geologist who uses physical principles to study the properties of the Earth: One famous geophysicist was Alfred Lothat Wegener (1880 - 1930) who put forward the theory of the continental drift.
Germanist
A student of or specialist in the German language, literature, and culture.