Yours, Etc.: Origins and Uses of 8 Sign-Offs
1650s (implied in sporadical), from Medieval Latin sporadicus "scattered," from Greek sporadikos "scattered," from sporas (genitive sporados) "scattered," from spora "a sowing" (see spore). Originally a medical term, "occurring in scattered instances;" the meaning "happening at intervals" is first recorded 1847. Related: Sporadically.
sporadic spo·rad·ic (spə-rād'ĭk, spô-) or spo·rad·i·cal (-ĭ-kəl)
Occurring at irregular intervals.
Occurring singly; not grouped.