The Collaborative International Dictionary of English v.0.48:

Thammuz \Tham"muz\, Tammuz \Tam"muz\, n. [Heb. thamm[=u]z.]
   1. A deity among the ancient Syrians, in honor of whom the
      Hebrew idolatresses held an annual lamentation. This deity
      has been conjectured to be the same with the Phoenician
      Adon, or Adonis. --Milton.
      [1913 Webster]

   2. The fourth month of the Jewish ecclesiastical year, --
      supposed to correspond nearly with our month of July.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Tammuz
    n 1: the tenth month of the civil year; the fourth month of the
         ecclesiastic year (in June and July) [syn: Tammuz,
         Thammuz]
    2: Sumerian and Babylonian god of pastures and vegetation;
       consort of Inanna [syn: Dumuzi, Tammuz]

Easton's 1897 Bible Dictionary:

Tammuz
   a corruption of Dumuzi, the Accadian sun-god (the Adonis of the
   Greeks), the husband of the goddess Ishtar. In the Chaldean
   calendar there was a month set apart in honour of this god, the
   month of June to July, the beginning of the summer solstice. At
   this festival, which lasted six days, the worshippers, with loud
   lamentations, bewailed the funeral of the god, they sat "weeping
   for Tammuz" (Ezek. 8:14).

     The name, also borrowed from Chaldea, of one of the months of
   the Hebrew calendar.


Hitchcock's Bible Names Dictionary (late 1800's):

Tammuz, abstruse; concealed; consumed