-ist

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

humorist (s), humorists (pl) (nouns)
1. Someone who acts, speaks, or writes in an amusing way; such as, a comedian.
2. Anyone known to be amusing and to have a quick wit.
3. A person who writes, or performs, comic material.
hydrologist
1. Someone who is skilled in hydrology.
2. A practitioner of hydrology who works within the fields of either earth or environmental science, or civil and environmental engineering.
hydroponicist
Someone who is a specialist in hydroponics; that is, growing plants without soil, in beds of sand, gravel, or similar supporting material flooded with nutrient solutions.
hydrotherapist
A specialist in or practitioner of hydrotherapy.
hyetologist
hygeist
Someone who is a specialist in hygiene; a sanitarian.
hygienist
1. One who is skilled in the science of health and its maintenance. Synonym: hygieist.
2. Someone who specializes in hygiene, or in a specific branch of hygiene, such as, a dental hygienist.
hylologist
hylopathist
hylotheist (s) (noun), hylotheists (pl)
A person who believes that God and the material world are the same.
hylozoist
hypernephelist
Someone who goes above and beyond the clouds.
hypertrichologist
A person who treats unsightly facial hair.
hypnologist
A specialist in the phenomena of sleep and/or hypnosis.
hypnotist
Someone who practices hypnotism.