periodic
US
UK periodic adj: (recurring regularly)
SC 周期性的，周期的 zhōu qī de
SC 定期的 dìng qī de
The dentist recommends periodic cleanings.
periodic table, periodic table of elements n: (chart of the chemical elements)
SC 元素周期表 yuán sù zhōu qī biǎo
The noble gases are in the last column of the periodic table.