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]