periodic
/ˌpɪərɪˈɒdɪk/adjective
1
- appearing or occurring at intervals间歇的; 周期（性）的; 时而出现（或发生）的：
the periodic visits she made to her father.
她对她父亲的定期探望。
2
- Chemistry relating to the periodic table of the elements or the pattern of chemical properties which underlies it【化】元素周期表的; （周期表中）元素化学性能变化周期的：
the periodic law.
周期律。
3
- of or relating to a rhetorical period完整句的。见PERIOD（义项 6）。
词源
mid 17th cent.: from French périodique, or via Latin from Greek periodikos 'coming round at intervals', from periodos （see PERIOD）.