(grammar) A sentence whose main clause appears at the end, after other, especially dependent, clauses. / (physics) A structure made of bays coupled through one or more coordinates.

plural of periodic structure

(chemistry) The principle that chemical properties of the elements are periodic functions of their atomic numbers

plural of periodic function

(astronomy) Taking over 200 years to complete an orbit; especially said of comets.

Any of certain species of cicadas, especially in genus Magicicada, which are known for their 17- and 13-year life-cycles, during most of which they develop underground, emerging in large numbers for a short time as large and audible adults, all those emerging in a year constituting a brood.

plural of e-periodical

A periodical published in electronic format to be read on a computer or similar device.

plural of periodic comet

plural of periodical comet