The Collaborative International Dictionary of English v.0.48:

Respire \Re*spire"\ (r?*sp?r), v. i. [imp. & p. p. Respired
   (-sp?rd"); p. pr. & vb. n. Respiring.] [L. respirare,
   respiratum; pref. re- re- + spirare to breathe: cf. F.
   respirer. See Spirit.]
   1. To take breath again; hence, to take rest or refreshment.
      --Spenser.
      [1913 Webster]

            Here leave me to respire.             --Milton.
      [1913 Webster]

            From the mountains where I now respire. --Byron.
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   2. (Physiol.) To breathe; to inhale air into the lungs, and
      exhale it from them, successively, for the purpose of
      maintaining the vitality of the blood.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Respire \Re*spire"\, v. t.
   1. To breathe in and out; to inspire and expire,, as air; to
      breathe.
      [1913 Webster]

            A native of the land where I respire
            The clear air for a while.            --Byron.
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   2. To breathe out; to exhale. [R.] --B. Jonson.
      [1913 Webster]

WordNet (r) 3.0 (2006):

respire
    v 1: breathe easily again, as after exertion or anxiety
    2: undergo the biomedical and metabolic processes of respiration
       by taking up oxygen and producing carbon monoxide
    3: draw air into, and expel out of, the lungs; "I can breathe
       better when the air is clean"; "The patient is respiring"
       [syn: breathe, take a breath, respire, suspire]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "respire":
   be alive, be animate, blow, breathe, breathe hard, breathe in,
   breathe out, cough, draw breath, exhale, exhaust, exist, expel,
   expire, fetch breath, gasp, gulp, hack, have life, hiccup, huff,
   inhale, inspire, live, live and breathe, pant, puff, sigh, sneeze,
   sniff, sniffle, snore, snort, snuff, snuffle, subsist,
   walk the earth, wheeze