-ist

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

sensualist (s) (noun), sensualists (pl)
A person who likes, pursues, or indulges too much in the pleasures of life: Sharon was a sensualist who often spent time in the whirlpool bath because it was such a wonderful feeling for her to be there.
separatist
serendipitist (s) (noun), serendipitists (pl)
Someone who makes happy and unexpected discoveries unintentionally.
serialist
Someone who uses the method of musical composition in which all twelve chromatic tones of the octave appear in strict order.
sericulturalist
Someone who is involved with the production of raw silk and the rearing of silkworms for the purpose of producing silk.
sericulturist
Someone who is involved in sericulture or who grows silk-worms for the production of silk.
serologist
An expert in the science of the properties and reactions of serums, especially blood serum.
sesquilinguist
Someone who knows one and "a half" languages (or one and "part" of another language).
sesquipedalianist (s) (noun), sesquipedalianist (pl)
A person who uses excessively long words: "The vocabulary class had a contest to see which sesquipedalianists could come up with presentations of simple proverbs that have been turned into multi-syllable words."
silviculturist
sinoclamephilist
A collector of Chinaware.
Sinologist, sinologist (s); Sinologists, sinologists (pl) (nouns)
A student of Chinese history, language, and culture.
slabophilist
A collector of decorated tiles.
socialist
1. Someone who believes in or supports socialism or a socialist party.
2. An advocate of socialism or someone who is a member of a socialist party.
sodomist
One who practices sodomy.