The Collaborative International Dictionary of English v.0.48:

Ubiquity \U*biq"ui*ty\ ([-u]*b[i^]k"w[i^]*t[y^]), n. [L. ubique
   everywhere, fr. ubi where, perhaps for cubi, quobi (cf.
   alicubi anywhere), and if so akin to E. who: cf. F.
   ubiquit['e].]
   1. Existence everywhere, or in all places, at the same time;
      omnipresence; as, the ubiquity of God is not disputed by
      those who admit his existence.
      [1913 Webster]

            The arms of Rome . . . were impeded by . . . the
            wide spaces to be traversed and the ubiquity of the
            enemy.                                --C. Merivale.
      [1913 Webster]

   2. (Theol.) The doctrine, as formulated by Luther, that
      Christ's glorified body is omnipresent.
      [1913 Webster]

WordNet (r) 3.0 (2006):

ubiquity
    n 1: the state of being everywhere at once (or seeming to be
         everywhere at once) [syn: ubiquity, ubiquitousness,
         omnipresence]

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "ubiquity":
   completeness, comprehensiveness, entireness, entirety, eternity,
   everywhereness, exhaustiveness, glory, holiness, immutability,
   inclusiveness, infinite goodness, infinite justice, infinite love,
   infinite mercy, infinite power, infinite wisdom, infinity,
   intactness, integrality, integrity, light, majesty, omnipotence,
   omnipotency, omnipresence, omniscience, omnisciency, pervasiveness,
   solidarity, solidity, sovereignty, thoroughness, totality, unity,
   universality, wholeness



The Devil's Dictionary (1881-1906):

UBIQUITY, n.  The gift or power of being in all places at one time,
but not in all places at all times, which is omnipresence, an
attribute of God and the luminiferous ether only.  This important
distinction between ubiquity and omnipresence was not clear to the
mediaeval Church and there was much bloodshed about it.  Certain
Lutherans, who affirmed the presence everywhere of Christ's body were
known as Ubiquitarians.  For this error they were doubtless damned,
for Christ's body is present only in the eucharist, though that
sacrament may be performed in more than one place simultaneously.  In
recent times ubiquity has not always been understood -- not even by
Sir Boyle Roche, for example, who held that a man cannot be in two
places at once unless he is a bird.