noun

• (historical) A type of round shield borne by ancient Greek soldiers.
  ""shield both large and tough" has never said that aspides are small and weak […]"
• (archaic) An asp or generic venomous snake
  "Flesh dipped in the sea Ægeum will never be sweet; the herb Trigion being once bit with an aspis never groweth, and conscience once stained with innocent blood is always tied to a guilty remorse."
• (palynology) A prominent ring of thickened exine around a pore on a pollen grain
  "As might be expected, characters of the aspides themselves are not of much value in pollen identification, but they are easily recognized and many three-pored, aspidate grains are broadly categorized as "betuloid" in studies of airborne pollen."