\E*quiv"a*lent\, a. [L. aequivalens, -entis, p. pr.
of aequivalere to have equal power; aequus equal + valere to
be strong, be worth: cf. F. ['e]quivalent. See {Equal}, and
{Valiant}.]
1. Equal in wortir or value, force, power, effect, import,
   and the like; alike in significance and value; of the same
   import or meaning.
         For now to serve and to minister, servile and
         ministerial, are terms equivalent.    --South.
2. (Geom.) Equal in measure but not admitting of
   superposition; -- applied to magnitudes; as, a square may
   be equivalent to a triangle.
3. (Geol.) Contemporaneous in origin; as, the equivalent
   strata of different countries.

\E*quiv"a*lent\, n.
1. Something equivalent; that which is equal in value, worth,
   weight, or force; as, to offer an equivalent for damage
   done.
         He owned that, if the Test Act were repealed, the
         Protestants were entitled to some equivalent. . . .
         During some weeks the word equivalent, then lately
         imported from France, was in the mouths of all the
         coffeehouse.                          --Macaulay.
2. (Chem.) That comparative quantity by weight of an element
   which possesses the same chemical value as other elements,
   as determined by actual experiment and reference to the
   same standard. Specifically:
   (a) The comparative proportions by which one element
       replaces another in any particular compound; thus, as
       zinc replaces hydrogen in hydrochloric acid, their
       equivalents are 32.5 and 1.
   (b) The combining proportion by weight of a substance, or
       the number expressing this proportion, in any
       particular compound; as, the equivalents of hydrogen
       and oxygen in water are respectively 1 and 8, and in
       hydric dioxide 1 and 16.
Note: This term was adopted by Wollaston to avoid using the
      conjectural expression atomic weight, with which,
      however, for a time it was practically synonymous. The
      attempt to limit the term to the meaning of a
      universally comparative combining weight failed,
      because of the possibility of several compounds of the
      substances by reason of the variation in combining
      power which most elements exhibit. The equivalent was
      really identical with, or a multiple of submultiple of,
      the atomic weight.
3. (Chem.) A combining unit, whether an atom, a radical, or a
   molecule; as, in acid salt two or more equivalents of acid
   unite with one or more equivalents of base.
{Mechanical equivalent of heat} (Physics), the number of
   units of work which the unit of heat can perform; the
   mechanical energy which must be expended to raise the
   temperature of a unit weight of water from 0[deg] C. to
   1[deg] C., or from 32[deg] F. to 33[deg] F. The term was
   introduced by Dr. Mayer of Heilbronn. Its value was found
   by Joule to be 1390 foot pounds upon the Centigrade, or
   772 foot pounds upon the Fahrenheit, thermometric scale,
   whence it is often called {Joule's equivalent}, and
   represented by the symbol J. This is equal to 424 kilogram
   meters (Centigrade scale). A more recent determination by
   Professor Rowland gives the value 426.9 kilogram meters,
   for the latitude of Baltimore.

\E*quiv"a*lent\, v. t.
To make the equivalent to; to equal; equivalence. [R.]