The Collaborative International Dictionary of English v.0.48:

Quaver \Qua"ver\, v. t.
   To utter with quavers.
   [1913 Webster]

         We shall hear her quavering them . . . to some
         sprightly airs of the opera.             --Addison.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quaver \Qua"ver\, n.
   1. A shake, or rapid and tremulous vibration, of the voice,
      or of an instrument of music.
      [1913 Webster]

   2. (Mus.) An eighth note. See Eighth.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Quaver \Qua"ver\, v. i. [imp. & p. p. Quavered; p. pr. & vb.
   n. Quavering.] [OE. quaven to shake, to tremble; cf. LG.
   quabbeln to shake, to be soft, of fat substances, quabbe a
   fat lump of flesh, a dewlap, D. kwabbe, and E. quiver, v.]
   1. To tremble; to vibrate; to shake. --Sir I. Newton.
      [1913 Webster]

   2. Especially, to shake the voice; to utter or form sound
      with rapid or tremulous vibrations, as in singing; also,
      to trill on a musical instrument
      [1913 Webster]

WordNet (r) 3.0 (2006):

quaver
    n 1: a tremulous sound
    2: a musical note having the time value of an eighth of a whole
       note [syn: eighth note, quaver]
    v 1: give off unsteady sounds, alternating in amplitude or
         frequency [syn: quaver, waver]
    2: sing or play with trills, alternating with the half note
       above or below [syn: warble, trill, quaver]

Moby Thesaurus II by Grady Ward, 1.0:

213 Moby Thesaurus words for "quaver":
   Bebung, accidental, anthem, aphonia, artificial voice, ballad, bob,
   bobble, bounce, break, breve, broken speech, broken tones,
   broken voice, bump, carol, chant, chatter, childish treble, chirp,
   chirrup, choir, choked voice, chorus, cracked voice, croak, croon,
   crotchet, crow, demisemiquaver, descant, didder, disquiet,
   disquietude, dither, dithers, do-re-mi, dominant, dominant note,
   double whole note, drawl, dysarthria, dyslalia, dyslogia,
   dysphasia, dysphonia, dysphrasia, eighth note, enharmonic,
   enharmonic note, falsetto, falter, fidget, fidgetiness, fidgets,
   flat, flip out, fluctuate, fluctuation, flutter, freak out on,
   get high on, glow, go pitapat, grimace, half note, harshness,
   have an ague, have the fidgets, have the shakes, hawking voice,
   heave, heaving, hemidemisemiquaver, hesitate, hiss, hoarseness,
   hum, hustle, hymn, idioglossia, idiolalia, impairment of speech,
   inquietude, intonate, intone, jactitate, jar, jerk, jig, jigget,
   jiggle, jog, joggle, jolt, jostle, jounce, jump, lilt, lisp,
   lisping, loss of voice, mince, minim, minstrel, musical note,
   muzzy speech, nasal tone, nasalization, natural, note, oscillate,
   oscillation, palpitate, palpitation, pant, panting, patent note,
   pipe, pitapat, pitter-patter, psalm, quake, quaking, quarter note,
   quavering, quiver, quivering, report, responding note,
   restlessness, rictus, roulade, semibreve, semiquaver, serenade,
   shake, shake all over, shakes, shaking, shaped note, sharp, shiver,
   shivers, shock, shudder, sibilation, sing, sing in chorus,
   sixteenth note, sixty-fourth note, sol-fa, solmizate,
   speech defect, speech impediment, spiccato, squirm, staccato,
   sustained note, swell, swell with emotion, talk incoherently,
   tercet, thirty-second note, thrill, thrill to, throb, throbbing,
   tic, tingle, tingle with excitement, tone, toss, toss and turn,
   tremble, trembling, tremolando, tremolant, tremolo, tremor,
   trepidation, trepidity, trill, trillet, trilleto, trillo, triplet,
   troll, tumble, turn on to, twang, tweedle, tweedledee,
   twist and turn, twit, twitch, twitter, unrest, vacillate, vibrate,
   vibration, vibrato, vocalize, warble, waver, wavering, whistle,
   whole note, wiggle, wobble, wriggle, writhe, yodel