The Collaborative International Dictionary of English v.0.48:

Correlative \Cor*rel"a*tive\ (k?r-r?l"?-t?v), a. [Cf. F.
   corr['e]latif.]
   Having or indicating a reciprocal relation.
   [1913 Webster]

         Father and son, prince and subject, stranger and
         citizen, are correlative terms.          --Hume.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Correlative \Cor*rel"a*tive\, n.
   1. One who, or that which, stands in a reciprocal relation,
      or is correlated, to some other person or thing. --Locke.
      [1913 Webster]

            Spiritual things and spiritual men are correlatives.
                                                  --Spelman.
      [1913 Webster]

   2. (Gram.) The antecedent of a pronoun.
      [1913 Webster]

WordNet (r) 3.0 (2006):

correlative
    adj 1: mutually related [syn: correlative, correlate,
           correlated]
    2: expressing a reciprocal or complementary relation;
       "correlative conjunctions"
    n 1: either of two or more related or complementary variables
         [syn: correlate, correlative]

Moby Thesaurus II by Grady Ward, 1.0:

64 Moby Thesaurus words for "correlative":
   accessory, accompanying, affinitive, agnate, akin, allied,
   analogical, analogous, appertaining, associated, associative,
   attendant, attending, cognate, coincident, collatable, collateral,
   combined, commensurable, commensurate, comparable, comparative,
   concomitant, concurrent, congeneric, congenerous, congenial,
   conjoint, connate, connatural, connected, connective, conspecific,
   corelated, corelational, corelative, correlated, correlational,
   coupled, en rapport, enate, fellow, joined, joint, linking,
   matchable, much at one, mutual, paired, parallel, pertaining,
   pertinent, proportionable, proportional, proportionate, referable,
   referring, relating, relational, relative, similar, simultaneous,
   sympathetic, twin



Bouvier's Law Dictionary, Revised 6th Ed (1856):

CORRELATIVE. This term is used to designate those things, one of which
cannot exist without another; for example, father and child; mountain and
valley, &c. Law, obligation, right, and duty, are therefore correlative to
each other.