Source : Webster's Revised Unabridged Dictionary (1913)

Serpens \Ser"pens\, n. [L. See {Serpent}.] (Astron.)
   A constellation represented as a serpent held by
   Serpentarius.

Source : WordNet®

Serpens
     n : a constellation in the equatorial region of the northern
         hemisphere near Ophiuchus and Corona Borealis