\De*cliv"i*ty\, n.; pl. {Declivities}. [L. declivitas,
fr. declivis sloping, downhill; de + clivus a slope, a hill;
akin to clinare to incline: cf. F. d['e]clivit['e]. See
{Decline}.]
1. Deviation from a horizontal line; gradual descent of
   surface; inclination downward; slope; -- opposed to
   acclivity, or ascent; the same slope, considered as
   descending, being a declivity, which, considered as
   ascending, is an acclivity.
2. A descending surface; a sloping place.
         Commodious declivities and channels for the passage
         of the waters.                        --Derham.