This is the 1543rd most frequent Russian word.
причин
"Причин" is the genitive plural form of "причина," meaning "reasons" or "causes."
The word "причин" is used in plural form, meaning 'reasons', in the context of explaining causes or motivations for joy.
У него есть много причин для радости.
He has many reasons for joy.
Here, "причин" in plural is used again in the context of identifying causes or triggers for worry.
Мы не нашли никаких причин для беспокойства.
We did not find any reasons for concern.
The word "причины" in plural nominative case is used to describe a set of reasons that are described or presented.