The Collaborative International Dictionary of English v.0.48:

Jehovah \Je*ho"vah\, n. [Heb. usually y[e^]h[=o]v[=a]h (with the
   vowel points of [a^]d[=o]n[=a]i Lord), sometimes (to avoid
   repetition) y[e^]h[=o]vih (with the vowel points of
   [e^]l[=o]h[imac]m God); but only the four Heb, consonants
   yhvh are conceded to be certainly known.]
   A Scripture name of the Supreme Being, by which he was
   revealed to the Jews as their covenant God or Sovereign of
   the theocracy; the "ineffable name" of the Supreme Being,
   which was not pronounced by the Jews.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Yahweh \Yah"weh\ (y[aum]"w[e^]), Yahwe \Yah"we\, prop. n. Also
Jahveh \Jah"veh\ (y[aum]"w[e^]), Jahve \Jah"ve\, Yahve \Yahve\,
Yahveh \Yahveh\, etc.
   A modern transliteration of the Hebrew word translated
   Jehovah in the Bible; -- used by some critics to
   discriminate the tribal god of the ancient Hebrews from the
   Christian Jehovah. Yahweh or Yahwe is the spelling now
   generally adopted by scholars.

   Syn: Yahwe, Yahveh, Wahvey, Jahve, Jahveh, Jahvey, Jahweh,
        Jehovah.
        [Webster 1913 Suppl. +WordNet 1.5 +CM] Jahvism

WordNet (r) 3.0 (2006):

Jehovah
    n 1: a name for the God of the Old Testament as transliterated
         from the Hebrew consonants YHVH [syn: Yahweh, YHWH,
         Yahwe, Yahveh, YHVH, Yahve, Wahvey, Jahvey,
         Jahweh, Jehovah, JHVH]
    2: terms referring to the Judeo-Christian God [syn: Godhead,
       Lord, Creator, Maker, Divine, God Almighty,
       Almighty, Jehovah]