periodic
adjectiveUK /ˌpɪəriˈɒdɪk/
US /ˌpɪriˈɑːdɪk/
Happening again and again after a certain amount of time.
The library sends a periodic reminder to return overdue books.
OTHER MEANINGS
2. Happening at regular intervals of time, especially in science.
The periodic motion of the pendulum kept the clock ticking.
3. Relating to a publication that comes out at regular intervals.
She writes for a periodic journal about local history.
4. Relating to the periodic table of chemical elements.
Hydrogen is the first element in the periodic table.