The Collaborative International Dictionary of English v.0.48:

Banns \Banns\ (b[a^]nz), n. pl. [See Ban.]
   Notice of a proposed marriage, proclaimed in a church, or
   other place prescribed by law, in order that any person may
   object, if he knows of just cause why the marriage should not
   take place.
   [1913 Webster]

WordNet (r) 3.0 (2006):

banns
    n 1: a public announcement of a proposed marriage

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "banns":
   Gretna Green wedding, affiance, banns of matrimony, betrothal,
   betrothment, bridal, bridal suite, bridechamber, chuppah,
   church wedding, civil ceremony, civil wedding, elopement,
   engagement, epithalamium, espousal, espousals, espousement,
   forced marriage, handfasting, honeymoon, hymen, hymeneal,
   hymeneal rites, marriage, marriage contract, nuptial apartment,
   nuptial mass, nuptial song, nuptials, plighted faith,
   plighted troth, prothalamium, saffron veil, shotgun wedding,
   spousals, troth, wedding, wedding canopy, wedding song,
   wedding veil