Waning

waning
    adj 1: (of the Moon) pertaining to the period during which the
           visible surface of the moon decreases; "after full moon
           comes the waning moon" [ant: {waxing}]
    n 1: a gradual decrease in magnitude or extent; "the waning of
         his enthusiasm was obvious"; "the waxing and waning of the
         moon" [ant: {waxing}]
    

Wane \Wane\, v. i. [imp. & p. p. {Waned}; p. pr. & vb. n.
   {Waning}.] [OE. wanien, AS. wanian, wonian, from wan, won,
   deficient, wanting; akin to D. wan-, G. wahnsinn, insanity,
   OHG. wan, wana-, lacking, wan?n to lessen, Icel. vanr
   lacking, Goth. vans; cf. Gr. ? bereaved, Skr. ?na wanting,
   inferior. ????. Cf. {Want} lack, and {Wanton}.]
   [1913 Webster]
   1. To be diminished; to decrease; -- contrasted with {wax},
      and especially applied to the illuminated part of the
      moon.
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            Like the moon, aye wax ye and wane.
            Waning moons their settled periods keep. --Addison.
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   2. To decline; to fail; to sink.
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            You saw but sorrow in its waning form. --Dryden.
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            Land and trade ever will wax and wane together.
                                                  --Sir J.
                                                  Child.
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Waning \Wan"ing\, n.
   The act or process of waning, or decreasing.
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         This earthly moon, the Church, hath fulls and wanings,
         and sometimes her eclipses.              --Bp. Hall.
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95 Moby Thesaurus words for "waning":
      aging, at rest, calm, cloistered, coming apart, contractive, cool,
      cracking, crumbling, decadent, declining, decreasing, decrescendo,
      decrescent, degenerate, deliquescent, deteriorating, diminishing,
      diminuendo, disintegrating, doting, draining, drooping, dwindling,
      dying, ebbing, effete, even-tenored, fading, failing, falling,
      flagging, fragmenting, getting on, going to pieces, growing old,
      halcyon, hushed, impassive, isolated, languishing, lessening,
      marcescent, moldering, on the wane, pacific, peaceable, peaceful,
      pining, placid, quiescent, quiet, receding, reductive, regressive,
      reposeful, reposing, restful, resting, retiring, retreating,
      retrograde, retrogressive, secluded, senescent, sequestered,
      sequestrated, sheltered, shrinking, shriveling, sinking, sliding,
      slipping, slumping, smooth, still, still as death, stillish,
      stilly, stoic, stolid, subsiding, tabetic, tranquil, unagitated,
      undisturbed, unmoved, unperturbed, unruffled, unstirring,
      untroubled, wasting, wilting, withering, worsening