\Dec"re*ment\, n. [L. decrementum, fr. decrescere. See
{Decrease}.]
1. The state of becoming gradually less; decrease;
   diminution; waste; loss.
         Twit me with the decrements of my pendants. --Ford.
         Rocks, mountains, and the other elevations of the
         earth suffer a continual decrement.   --Woodward.
2. The quantity lost by gradual diminution or waste; --
   opposed to {increment}.
3. (Crystallog.) A name given by Ha["u]y to the successive
   diminution of the layers of molecules, applied to the
   faces of the primitive form, by which he supposed the
   secondary forms to be produced.
4. (Math.) The quantity by which a variable is diminished.
{Equal decrement of life}.
   (a) The decrease of life in a group of persons in which
       the assumed law of mortality is such that of a given
       large number of persons, all being now of the same
       age, an equal number shall die each consecutive year.
   (b) The decrease of life in a group of persons in which
       the assumed law of mortality is such that the ratio of
       those dying in a year to those living through the year
       is constant, being independent of the age of the
       persons.