The Collaborative International Dictionary of English v.0.48:

Precipitous \Pre*cip"i*tous\, a. [L. praeceps, -cipitis: cf. OF.
   precipiteux. See Precipice.]
   1. Steep, like a precipice; as, a precipitous cliff or
      mountain.
      [1913 Webster]

   2. Headlong; as, precipitous fall.
      [1913 Webster]

   3. Hasty; rash; quick; sudden; precipitate; as, precipitous
      attempts. --Sir T. Browne. "Marian's low, precipitous
      `Hush!'" --Mrs. Browning.
      [1913 Webster] -- Pre*cip"i*tous*ly, adv. --
      Pre*cip"i*tous*ness, n.
      [1913 Webster]

WordNet (r) 3.0 (2006):

precipitousness
    n 1: the property possessed by a slope that is very steep [syn:
         abruptness, precipitousness, steepness] [ant:
         gentleness, gradualness]
    2: the quality of happening with headlong haste or without
       warning [syn: abruptness, precipitateness,
       precipitousness, precipitance, precipitancy,
       suddenness]