This is the 6939th most frequent Turkish word.
cem
"Cem" in Turkish means "gathering" or "assembly."
Here, 'Cem' is used as a proper noun, the name of a person, referring specifically to the individual named Cem.
Cem arkadaşlarıyla parkta buluştu.
Cem met his friends at the park.
In this sentence, 'cem' is part of a phrase ('cem evi') and refers to the spiritual gathering often associated with Alevi practices.
Gece cem evinde toplandılar.
They gathered in the worship house during the night.
Here, 'cem' is used as a common noun meaning 'gathering' or 'assembly' in Turkish.