The Collaborative International Dictionary of English v.0.48:

Swoon \Swoon\, n.
   A fainting fit; syncope.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Swoon \Swoon\, v. i. [imp. & p. p. Swooned; p. pr. & vb. n.
   Swooning.] [OE. swounen, swoghenen, for swo?nien, fr.
   swo?en to sigh deeply, to droop, AS. sw[=o]gan to sough,
   sigh; cf. gesw[=o]gen senseless, swooned, gesw[=o]wung a
   swooning. Cf. Sough.]
   To sink into a fainting fit, in which there is an apparent
   suspension of the vital functions and mental powers; to
   faint; -- often with away.
   [1913 Webster]

         The sucklings swoon in the streets of the city. --Lam.
                                                  ii. 11.
   [1913 Webster]

         The most in years . . . swooned first away for pain.
                                                  --Dryden.
   [1913 Webster]

         He seemed ready to swoon away in the surprise of joy.
                                                  --Tatler.
   [1913 Webster]

WordNet (r) 3.0 (2006):

swoon
    n 1: a spontaneous loss of consciousness caused by insufficient
         blood to the brain [syn: faint, swoon, syncope,
         deliquium]
    v 1: pass out from weakness, physical or emotional distress due
         to a loss of blood supply to the brain [syn: faint,
         conk, swoon, pass out]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "swoon":
   KO, black out, blackout, catalepsy, catatonia, catatony, coma,
   crap out, die away, drop, drown, encephalitis lethargica, faint,
   fall senseless, gray out, grayout, high, kayo, keel over, knockout,
   lethargy, lipothymia, lipothymy, narcohypnosis, narcolepsy,
   narcoma, narcosis, narcotic stupor, narcotization, nirvana,
   nirvana principle, nod, nothingness, oblivion, obliviousness,
   pass out, sedation, semiconsciousness, senselessness, shock, sleep,
   sleeping sickness, sopor, stupor, succumb, syncope, thanatosis,
   trance, unconsciousness