Next week Thursday and Friday are Rosh Chodesh for the month of Tammuz. Now, it is well known that the names of the months of the English calendar that we use have origins from ancient Rome. Some have the names of famous emperors, like July which is named after Julius Caesar and August which is named after Augustus. Some months are named after gods. Like January which comes from Janus, the two-faced sky god and March which comes from Mars, the god of war.
So it should not strike any learned Jew as surprising that a number of months in the Jewish calendar are likewise taken from Pagan sources as well, especially as it is obvious that we no longer use any of the names of months found in Tanach. Most of the modern Jewish months are borrowed from the Babylonian names, some of which follow the names of gods (and some of which are derived from even older sources). But here I'm going to focus on just one month, Tammuz.
I like Wikipedia, so here's what it has to say about the issue:
"In Babylonia, the month Tammuz was established in honor of the eponymous god Tammuz, who originated as an Akkadian shepherd-god, Dumuzid or Dumuzi, the consort of Ishtar and the parallel of the Syrian Adonis who was drawn into the Greek pantheon. The name "Tammuz" seems to have been derived from the Akkadian form Tammuzi, based on early Sumerian Damu-zid. The later standard Sumerian form, Dumu-zid, in turn became Dumuzi in Akkadian. Beginning with the summer solstice came a time of mourning in the Ancient Near East as in the Aegean: the Babylonians marked the decline in daylight hours and the onset of killing summer heat and drought with a six-day "funeral" for the god that was observed even at the very door of the Temple in Jerusalem, to the horror of the reformer Ezekiel:
"Then he brought me to the door of the gate of the Lord's house which was toward the north; and, behold, there sat women weeping for Tammuz. Then said he unto to me, 'Hast thou seen this, O son of man? turn thee yet again, and thou shalt see greater abominations than these." — Ezekiel 8.14-15"
That was some good information about the history of the name, but let's go to godchecker.com to get more information about the myth itself and why such a god would be so honored with a month of its own:
TAMMUZ: Akkadian God of Vegetation and Agriculture who regulates the seasons and symbolises Death and Rebirth in nature. Somewhat reluctantly, it appears.
Every summer, when his powers are strongest, when the flowers are blooming and the harvests are looking great, he collapses from heat exhaustion and dies. His soul flees to the Underworld where it's nice and cool, leaving the world's vegetation to fend for itself.
The resulting desolation causes much misery as plants decay and winter sets in. So his mourning wife Ishtar nips down to the nether regions to rescue him. Which is such a complicated and arduous task that it always takes six months and by the time they reappear, spring is right on schedule.
So as we see even in Tanach, people mourned his death each year since it was signified the end of spring. Alrighty then. While some Jews might have issue with such Jewish borrowing and might even deny it entirely (I saw one place where they claimed that Tammuz is Aramaic for "heating up." Patently false though, Dumuzi is Akkadian for "rightful son") Tanach itself speaks against them because in the only time it uses the term Tammuz is in reference to a pagan deity.
A last point I'd like to acknowledge is the matter of the mourning. Isn't it curious that a month of mourning which was popular throughout the ancient Near East (from Sumer and Babylon to the Aegean) is the same month used by Judaism for mourning in Judaism? Sure, there may be good historical reasons why we fast on the 17th of Tammuz and then go into the time of the Three Weeks, but would it have been as big an annual commemoration had there not already been such a precedent of mourning during that time period?