Emily Dickinson Lexicon

SPO-RAD'IC, or SPO-RAD'IC-AL, a. [Fr. sporadique; Gr. σποραδικος, separate, scattered; whence certain isles of Greece were called Sporades.]

Separate; single; scattered; used only in reference to diseases. A sporadic disease, is one which occurs in single and scattered cases, in distinction from an epidemic and endemic, which affects many persons at the same time. Sporadic diseases are opposed to epidemics and endemics, as accidental, scattered complaints. – Parr.