The Collaborative International Dictionary of English v.0.48:

Downward \Down"ward\, Downwards \Down"wards\, adv. [AS.
   ad?nweard. See Down, adv., and -ward.]
   1. From a higher place to a lower; in a descending course;
      as, to tend, move, roll, look, or take root, downward or
      downwards. "Looking downwards." --Pope.
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            Their heads they downward bent.       --Drayton.
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   2. From a higher to a lower condition; toward misery,
      humility, disgrace, or ruin.
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            And downward fell into a groveling swine. --Milton.
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   3. From a remote time; from an ancestor or predecessor; from
      one to another in a descending line.
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            A ring the county wears,
            That downward hath descended in his house,
            From son to son, some four or five descents. --Shak.
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The Collaborative International Dictionary of English v.0.48:

Downward \Down"ward\, a.
   1. Moving or extending from a higher to a lower place;
      tending toward the earth or its center, or toward a lower
      level; declivous.
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            With downward force
            That drove the sand along he took his way. --Dryden.
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   2. Descending from a head, origin, or source; as, a downward
      line of descent.
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   3. Tending to a lower condition or state; depressed;
      dejected; as, downward thoughts. --Sir P. Sidney.
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WordNet (r) 3.0 (2006):

downward
    adv 1: spatially or metaphorically from a higher to a lower
           level or position; "don't fall down"; "rode the lift up
           and skied down"; "prices plunged downward" [syn: down,
           downwards, downward, downwardly] [ant: up,
           upward, upwardly, upwards]
    adj 1: extending or moving from a higher to a lower place; "the
           down staircase"; "the downward course of the stream"
           [syn: down(a), downward(a)]
    2: on or toward a surface regarded as a base; "he lay face
       downward"; "the downward pull of gravity"

Moby Thesaurus II by Grady Ward, 1.0:

73 Moby Thesaurus words for "downward":
   adown, ascending, axial, back, back-flowing, backward, below,
   collapsing, deciduous, declining, declivitous, decurrent,
   descendant, descending, down, down south, down-reaching,
   down-trending, downcoming, downfalling, downgoing, downgrade,
   downhill, downline, downright, downsinking, downstairs, downstream,
   downstreet, downtown, downwards, downwith, drifting, drooping,
   dropping, falling, flowing, fluent, flying, going, gyrational,
   gyratory, mounting, on the descendant, on the downgrade, passing,
   plummeting, plunging, progressive, reflowing, refluent, regressive,
   retrogressive, rising, rotary, rotational, rotatory, running,
   rushing, sagging, setting, sideward, sinking, sliding, slipping,
   soaring, streaming, submerging, subsiding, tottering, tumbledown,
   up-trending, upward