Precipitous, a.
Etymology: [L. praeceps, -cipitis: cf. OF. precipiteux. See Precipice.]
1. Steep, like a precipice; as, a precipitous cliff or mountain.
2. Headlong; as, precipitous fall.
3. Hasty; rash; quick; sudden; precipitate; as, precipitous attempts. Sir T. Browne. "Marian's low, precipitous `Hush!'" Mrs. Browning. -- Pre*cip"i*tous*ly, adv. -- Pre*cip"i*tous*ness, n.
Shades of meaning
Fernald has no entry of its own for precipitous; he lists it under steep.
Where he writes about it:
A sharp ascent or descent is one that makes a sudden, decided angle with the plane from which it starts; a sheer ascent or descent is perpendicular, or nearly so; precipitous applies to that which is of the nature of a precipice, and is used especially of a descent; abrupt is as if broken sharply off, and applies to either acclivity or declivity. — from steep