In the Hindu calendar, Chaturdashi is the 14th day (Tithi) of the waxing phase or waning phase of the moon. This is the day prior to new moon (Amavasya) or full moon (Pournami). It has a great significance to Bengalis, as goddess Tara appeared to rishi vasistha on this tithi.
Chaturdasi means 14, wherein Chatur means four and Dasi means 10. It is taken from the Sanskrit.