The Collaborative International Dictionary of English v.0.48:

Hazardous \Haz"ard*ous\ (-[u^]s), a. [Cf. F. hasardeux.]
   Exposed to hazard; dangerous; risky.
   [1913 Webster]

         To enterprise so hazardous and high!     --Milton.

   Syn: Perilous; dangerous; bold; daring; adventurous;
        venturesome; precarious; uncertain. -- Haz"ard*ous*ly,
        adv. -- Haz"ard*ous*ness, n.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

hazardousness \haz"ard*ous*ness\ n.
   the state of being dangerous.

   Syn: perilousness, precariousness, danger.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

hazardousness
    n 1: the state of being dangerous [syn: hazardousness,
         perilousness]