Emily Dickinson Lexicon

PAR-EM'BO-LE, or PAR-EM'BO-LY, n. [Gr. παρεμβολη, insertion.]

In rhetoric, the insertion of something relating to the subject in the middle of a period. It differs from the parenthesis only in this: the parembole relates to the subject, the parenthesis is foreign from it. – Encyc. Vossius.