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