The Collaborative International Dictionary of English v.0.48:

Eridanus \E*rid"a*nus\, n. [L., fr. Gr. ?, the Greek name of the
   River Po.] (Anat.)
   A long, winding constellation extending southward from Taurus
   and containing the bright star Achernar.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Eridanus
    n 1: a constellation in the southern hemisphere near Fornax and
         Cetus