The Collaborative International Dictionary of English v.0.48:

Derivative \De*riv"a*tive\, a. [L. derivativus: cf. F.
   d['e]rivatif.]
   Obtained by derivation; derived; not radical, original, or
   fundamental; originating, deduced, or formed from something
   else; secondary; as, a derivative conveyance; a derivative
   word.
   [1913 Webster]

   2. Hence, unoriginal (said of art or other intellectual
      products.
      [PJC]

   Derivative circulation, a modification of the circulation
      found in some parts of the body, in which the arteries
      empty directly into the veins without the interposition of
      capillaries. --Flint. -- De*riv"a*tive*ly, adv. --
      De*riv"a*tive*ness, n.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Derivative \De*riv"a*tive\, n.
   1. That which is derived; anything obtained or deduced from
      another.
      [1913 Webster]

   2. (Gram.) A word formed from another word, by a prefix or
      suffix, an internal modification, or some other change; a
      word which takes its origin from a root.
      [1913 Webster]

   3. (Mus.) A chord, not fundamental, but obtained from another
      by inversion; or, vice versa, a ground tone or root
      implied in its harmonics in an actual chord.
      [1913 Webster]

   4. (Med.) An agent which is adapted to produce a derivation
      (in the medical sense).
      [1913 Webster]

   5. (Math.) A derived function; a function obtained from a
      given function by a certain algebraic process.
      [1913 Webster]

   Note: Except in the mode of derivation the derivative is the
         same as the differential coefficient. See Differential
         coefficient, under Differential.
         [1913 Webster]

   6. (Chem.) A substance so related to another substance by
      modification or partial substitution as to be regarded as
      derived from it; thus, the amido compounds are derivatives
      of ammonia, and the hydrocarbons are derivatives of
      methane, benzene, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

derivative
    adj 1: resulting from or employing derivation; "a derivative
           process"; "a highly derivative prose style"
    n 1: the result of mathematical differentiation; the
         instantaneous change of one quantity relative to another;
         df(x)/dx [syn: derived function, derivative,
         differential coefficient, differential, first
         derivative]
    2: a compound obtained from, or regarded as derived from,
       another compound
    3: a financial instrument whose value is based on another
       security [syn: derivative instrument, derivative]
    4: (linguistics) a word that is derived from another word;
       "`electricity' is a derivative of `electric'"