「周期的」と「定期的」はどう違いますか


The dictionary tells me that they both mean "periodic" so I can't actually
understand the difference. Can someone help me? Thank you so much!




定期的 is usually about human and societal things. If something is not
particularly associated with calendar months and years, like a natural
phenomenon, 周期的 would be better.

"first weekday of every month" is more 定期的 than 周期的. "every 1 millisecond" is
more 周期的 than 定期的.

It can be a matter of perspectives, though. When a scientist observes a human
behavior, they might use 周期的.

