aspis

plural aspides

1. historicalA type of round shield borne by ancient Greek soldiers.

   "shield both large and tough" has never said that aspides are small and weak […]

   1963, William Kurtz Wimsatt, What to Say About a Poem and Other Essays, page 39

2. archaicAn 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.

   1588, Robert Greene, “The History of Dorastus and Fawnia”, in Pandosto: The Triumph of Time, published 1907

3. biologyA 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.

   1974, Eugene Cecil Ogden, Manual for Sampling Airborne Pollen, →ISBN, page 128