The Collaborative International Dictionary of English v.0.48:

Moiety \Moi"e*ty\ (moi"[-e]*t[y^]), n.; pl. Moieties
   (moi"[-e]*t[i^]z). [F. moiti['e], L. medietas, fr. medius
   middle, half. See Mid, a., and cf. Mediate, Mediety.]
   1. One of two equal parts; a half; as, a moiety of an estate,
      of goods, or of profits; the moiety of a jury, or of a
      nation. --Shak.
      [1913 Webster]

            The more beautiful moiety of his majesty's subject.
                                                  --Addison.
      [1913 Webster]

   2. An indefinite part; a small part. --Shak.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Residue \Res"i*due\ (r?z"?-d?), n. [F. r['e]sidu, L. residuum,
   fr. residuus that is left behind, remaining, fr. residere to
   remain behind. See Reside, and cf. Residuum.]
   1. That which remains after a part is taken, separated,
      removed, or designated; remnant; remainder.
      [1913 Webster]

            The residue of them will I deliver to the sword.
                                                  --Jer. xv. 9.
      [1913 Webster]

            If church power had then prevailed over its victims,
            not a residue of English liberty would have been
            saved.                                --I. Taylor.
      [1913 Webster]

   2. (Law) That part of a testeator's estate wwhich is not
      disposed of in his will by particular and special legacies
      and devises, and which remains after payment of debts and
      legacies.
      [1913 Webster]

   3. (Chem.) That which remains of a molecule after the removal
      of a portion of its constituents; hence, an atom or group
      regarded as a portion of a molecule; a moiety or
      group; -- used as nearly equivalent to radical, but in
      a more general sense.
      [1913 Webster +PJC]

   Note: The term radical is sometimes restricted to groups
         containing carbon, the term residue and moiety being
         applied to the others.
         [1913 Webster]

   4. (Theory of Numbers) Any positive or negative number that
      differs from a given number by a multiple of a given
      modulus; thus, if 7 is the modulus, and 9 the given
      number, the numbers -5, 2, 16, 23, etc., are residues.
      [1913 Webster]

   Syn: Rest; remainder; remnant; balance; residuum; remains;
        leavings; relics.
        [1913 Webster]

WordNet (r) 3.0 (2006):

moiety
    n 1: one of two (approximately) equal parts [syn: moiety,
         mediety]
    2: one of two basic subdivisions of a tribe

Moby Thesaurus II by Grady Ward, 1.0:

118 Moby Thesaurus words for "moiety":
   allotment, allowance, ashram, big end, bigger half, bisection, bit,
   bite, body, budget, butt, caste, chip, chunk, clan, class, clip,
   clipping, collop, colony, commission, commonwealth, commune,
   community, contingent, crumb, cut, cutting, deal, destiny,
   dividend, division, dole, dollop, economic class, end,
   endogamous group, equal share, equidistance, extended family,
   family, fate, fifty percent, fifty-fifty, fragment, gens, gob,
   gobbet, half, half-and-half, halfway house, halver, helping,
   hemisphere, hunk, interest, kinship group, lot, lump, measure,
   mediety, meed, member, mess, mid-distance, midcourse,
   middle distance, midway, modicum, morsel, nuclear family, order,
   parcel, paring, part, particle, percentage, phratria, phratry,
   phyle, piece, portion, proportion, quantum, quota, rake-off,
   rasher, ration, scoop, scrap, section, segment, semicircle,
   semisphere, settlement, shard, share, shaving, shiver, shred,
   slice, sliver, small share, smithereen, snack, snatch, snip,
   snippet, social class, society, splinter, stake, stitch, stock,
   stump, subcaste, tatter, totem



Bouvier's Law Dictionary, Revised 6th Ed (1856):

MOIETY. The half of anything; as, if a testator bequeath one moiety of his
estate to A, and the other to B, each shall take an equal part. Joint
tenants are said to hold by moieties. Lit. 125; 3 M. G. & S. 274, 283