The Collaborative International Dictionary of English v.0.48:

Polyandry \Pol`y*an"dry\, n. [Poly- + Gr. 'anh`r, 'andro`s, man,
   male: cf. F. polyandrie.]
   The possession by a woman of more than one husband at the
   same time; -- contrasted with monandry.
   [1913 Webster]

   Note: In law, this falls under the head of polygamy.
         [1913 Webster]

WordNet (r) 3.0 (2006):

polyandry
    n 1: having more than one husband at a time

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "polyandry":
   beena marriage, bigamy, common-law marriage, companionate marriage,
   concubinage, deuterogamy, left-handed marriage, levirate,
   leviration, love match, marriage of convenience, monandry,
   monogamy, monogyny, morganatic marriage, picture marriage,
   polygamy, polygyny, trial marriage, trigamy



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

POLYANDRY. The state of a woman who has several husbands.
     2. Polyandry is legalized only in Tibet. This is inconsistent with the
law of nature. Vide Law of Nature.