The definition of periodic sentence is a sentence in which the main clause is given at the end of the sentence in order to create interest or suspense.
An example of periodic sentence is "I couldn't wait any longer, I went to sleep."
A sentence in which the main clause or its predicate is withheld until the end; for example,
Despite heavy winds and nearly impenetrable ground fog, the plane landed safely.
A sentence in which the essential elements, in the main clause, are withheld until the end or separated as by modifiers or subordinate clauses (Ex.: stock prices, as he had warned, had collapsed)
(rhetoric) A sentence whose main clause appears at its end.