Ĭn′fin-ĭ-tēs′ĭ-mal1, a.
a. [Fr. infinitésimal, Sp. infinitesimal, It. infinitesimale, from Fr. infinitésime, Sp. infinitesimo, It. infinitissimo, infinitely small, from Lat. infinitus. See INFINITE.] Infinitely small; less than any assignable quantity.