English meaning of the festival
Purnima literally means ‘full moon”. It occurs during Shukla Paksha (waxing phase of the moon). On Purnima the moon is fully illuminated.
How the date is decided annually
Purnima comes on the 15th thithi of the bright half (Shukla Paksha or waxing phase) of the lunar fortnight. The end of Purnima thithi marks the beginning of 15 days of Krishna Paksha (waning) phase of the moon.
Significance of the festival to Hinduism
Purnima is time for prayer, meditation, recitation of scriptures and mantras and fasting. These are done to strengthen ourselves mentally and spiritually. Fasting on Purnima day is considered highly auspicious as it bestows incomparable benefits and blessings on the devotees. Purnima vrat is devoted to Lord Vishnu and his avatars, especially Lord Sathyanarayan.
How to observe/practice
Purnima is the ideal day to do Sathyanarayan puja at homes. Many Hindu devotees observe a full day fast on Purnima day and offer prayers to Lord Vishnu.
Synonyms between major Indian languages
Pournami (Tamil & Telugu), Punam (Gujarati)