The Collaborative International Dictionary of English v.0.48:

Inject \In*ject"\, v. t. [imp. & p. p. Injected; p. pr. & vb.
   n. Injecting.] [L. injectus, p. p. of inicere, injicere, to
   throw in; pref. in- in + jacere to throw: cf. F. injecter.
   See Jet a shooting forth.]
   [1913 Webster]
   1. To throw in; to dart in; to force in; as, to inject cold
      water into a condenser; to inject a medicinal liquid into
      a cavity of the body; to inject morphine with a hypodermic
      syringe.
      [1913 Webster]

   2. Fig.: To throw; to offer; to propose; to instill.
      [1913 Webster]

            C[ae]sar also, then hatching tyranny, injected the
            same scrupulous demurs.               --Milton.
      [1913 Webster]

   3. To cast or throw; -- with on. [R.]
      [1913 Webster]

            And mound inject on mound.            --Pope.
      [1913 Webster]

   4. (Anat.) To fill (a vessel, cavity, or tissue) with a fluid
      or other substance; as, to inject the blood vessels.
      [1913 Webster]

   5. to add in; to insert; to interject; as, to inject a
      comment into the conversation; to inject humor into a
      tense situation.
      [PJC]

WordNet (r) 3.0 (2006):

inject
    v 1: give an injection to; "We injected the glucose into the
         patient's vein" [syn: inject, shoot]
    2: to introduce (a new aspect or element); "He injected new life
       into the performance"
    3: force or drive (a fluid or gas) into by piercing; "inject
       hydrogen into the balloon" [syn: inject, shoot]
    4: take by injection; "inject heroin"
    5: feed intravenously
    6: to insert between other elements; "She interjected clever
       remarks" [syn: interject, come in, interpose, put in,
       throw in, inject]

Moby Thesaurus II by Grady Ward, 1.0:

57 Moby Thesaurus words for "inject":
   animate, bathe, brew, bring in, douche, drench, drive in, drouk,
   ease in, embue, enliven, exhilarate, fire, flush, force in, imbrue,
   imbue, impregnate, infect, infiltrate, inform, infuse, inoculate,
   insert, insinuate, inspire, inspirit, interject, introduce,
   intromit, lave, leach, lixiviate, macerate, percolate, perfuse,
   permeate, pop in, put in, rinse, saturate, seethe, set in, slip in,
   soak, sodden, sop, souse, spirit, spirit up, steep, stick in,
   throw in, tuck in, wash, waterlog, whip in