The Collaborative International Dictionary of English v.0.48:

Symbiotic \Sym`bi*ot"ic\ ([i^]m`b[i^]*[o^]t"[i^]k), a. [Gr.
   symbiwtiko`s.] (Biol.)
   Pertaining to, or characterized by, or living in, a state of
   symbiosis. -- Sym`bi*ot"ic*al, a. -- Sym`bi*ot"ic*al*ly,
   adv.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Dependent \De*pend"ent\, a. [L. dependens, -entis, p. pr.
   dependere. See Depend, and cf. Dependant.]
   1. Hanging down; as, a dependent bough or leaf.
      [1913 Webster]

   2. Relying on, or subject to, something else for support; not
      able to exist, or sustain itself, or to perform anything,
      without the will, power, or aid of something else; not
      self-sustaining; subordinate; -- often with on or upon;
      as, dependent on God; dependent upon friends. Opposite of
      independent. [Narrower terms: interdependent,
      mutualist, mutually beneficial; parasitic, parasitical,
      leechlike, bloodsucking; subordinate; underage;
      myrmecophilous; symbiotic] Also See: unfree.
      [1913 Webster]

            England, long dependent and degraded, was again a
            power of the first rank.              --Macaulay.
      [1913 Webster]

   3. conditional; contingent or conditioned. Opposite of
      unconditional.

   Syn: qualified.
        [WordNet 1.5]

   4. addicted to drugs.

   Syn: addicted, dependent, drug-addicted, hooked, strung-out.
        [WordNet 1.5]

   Dependent covenant or Dependent contract (Law), one not
      binding until some connecting stipulation is performed.

   Dependent variable (Math.), a varying quantity whose
      changes are arbitrary, but are regarded as produced by
      changes in another variable, which is called the
      independent variable.
      [1913 Webster]

WordNet (r) 3.0 (2006):

symbiotic
    adj 1: used of organisms (especially of different species)
           living together but not necessarily in a relation
           beneficial to each

Moby Thesaurus II by Grady Ward, 1.0:

105 Moby Thesaurus words for "symbiotic":
   accompanying, accordant, affirmative, agreeable, agreeing,
   answerable, associate, associated, at one, at one with, coacting,
   coactive, coadjutant, coadjuvant, coadunate, coefficient,
   coexistent, coexisting, coherent, coincident, coinciding,
   collaborative, collective, collectivist, collectivistic, collusive,
   combined, combining, commensal, commensurate, common, communal,
   communalist, communalistic, communist, communistic, communitarian,
   compatible, concerted, concomitant, concordant, concurrent,
   concurring, conformable, congenial, congruent, congruous, conjoint,
   conniving, consentaneous, consentient, consilient, consistent,
   consonant, conspiratorial, cooperant, cooperating, cooperative,
   coordinate, correspondent, corresponding, coworking, ecological,
   ecotopic, ecumenic, en rapport, equivalent, fellow, harmonious,
   harmonized, in accord, in agreement, in rapport, in sync,
   in synchronization, inaccordance, inharmony, joint, like-minded,
   meeting, mutual, noncompetitive, of a piece, of like mind,
   of one mind, on all fours, parasitic, positive, proportionate,
   reciprocal, reconcilable, saprophytic, self-consistent,
   synchronized, synchronous, synergetic, synergic, synergistic,
   unanimous, uncompetitive, uniform, unisonant, unisonous, united,
   uniting