The Collaborative International Dictionary of English v.0.48:

Elisor \E*li"sor\, n. [F. ['e]liseur, fr. ['e]lire to choose, L.
   eligere. See Elect.] (Eng. Law)
   An elector or chooser; one of two persons appointed by a
   court to return a jury or serve a writ when the sheriff and
   the coroners are disqualified.
   [1913 Webster]