The Collaborative International Dictionary of English v.0.48:

Elopement \E*lope"ment\, n.
   The act of eloping; secret departure; -- said of a woman and
   a man, one or both, who run away from their homes for
   marriage or for cohabitation.
   [1913 Webster]

WordNet (r) 3.0 (2006):

elopement
    n 1: the act of running away with a lover (usually to get
         married)

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "elopement":
   AWOL, French leave, Gretna Green wedding, absence without leave,
   absquatulation, banns, bolt, bridal, bridal suite, bridechamber,
   chuppah, church wedding, civil ceremony, civil wedding, decampment,
   desertion, disappearance, disappearing act, epithalamium,
   espousals, espousement, exit, flight, forced marriage, fugitation,
   hasty retreat, hegira, honeymoon, hymen, hymeneal, hymeneal rites,
   marriage, nuptial apartment, nuptial mass, nuptial song, nuptials,
   prothalamium, quick exit, running away, saffron veil, scramming,
   shotgun wedding, skedaddle, skedaddling, spousals, wedding,
   wedding canopy, wedding song, wedding veil