The Collaborative International Dictionary of English v.0.48:

Catenary \Cat"e*na*ry\, n.; pl. Catenaries. (Geol.)
   The curve formed by a rope or chain of uniform density and
   perfect flexibility, hanging freely between two points of
   suspension, not in the same vertical line.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Catenary \Cat"e*na*ry\, Catenarian \Cat`e*na"ri*an\, a. [L.
   catenarius, fr. catena a chain. See Chain.]
   Relating to a chain; like a chain; as, a catenary curve.
   [1913 Webster]

WordNet (r) 3.0 (2006):

catenary
    n 1: the curve theoretically assumed by a perfectly flexible and
         inextensible cord of uniform density and cross section
         hanging freely from two fixed points