December in Thai is ธันวาคม pronounced tan-waa kom. Like all months (เดือน deuan) in Thai that have 31 days, it ends with คม (kom).
The abbreviated version of ธันวาคม is ธ.ค.
The beginning of ธันวาคม is ธนู (tá-noo) coming from the Sagittarius Zodiac sign. The reason for this is that months in Thai all come from zodiac signs.
King Bhumibol’s Birthday
This day Commemorates the day the King Bhumibol Adulyadej was born in 1927. Thai people also call this day Father’s day (วันพ่อ wan pôr).
The King’s death is commemorated in October as explained here.
Constitution Day (วันรัฐธรรมนูญ wan rát-tà-tam-má-noon) happens on December 10. This is a public holiday to commemorate when King Rama VII granted The first permanent Constitution of Thailand on December 10 1932.
I hope you learned how to say December in Thai ธันวาคม tan-waa kom and also learned about 2 national Thai Holidays.