Thaipusam (Tamil: தைப்பூசம்) is a Hindu festival celebrated mostly by the Tamil community on the full moon in the Tamil month of Thai (Jan/Feb). It is also referred to as Thaipooyam or Thaippooyam in the Malayalam language. Pusam refers to a star that is at its highest point during the festival. The festival commemorates both the birthday of Lord Murugan (also Subramaniam), the youngest son of Shiva and Parvati, and the occasion when Parvati gave Murugan a vel (spear) so he could vanquish the evil demon Soorapadman.
(more at wikipedia)