Purnima (also called Poornima, Pournima, Sanskrit: पूर्णिमा (IAST: pūrṇimā)) is the Indian and Nepali word for Full Moon. The day of Purnima is the day (Tithi) in each month in which the full moon occurs, and marks the division in each month between the two lunar fortnights (Paksha). The Shukla ("bright") Paksha is the fortnight before, and the Krishna ("dark") Paksha is the fortnight after, Purnima.
The following festivals occur on Purnima.Kartik Poornima, is celebrated on the full moon day of Kartik of Nepali Calendar. It is also called Tripura Purnima.
Shravan Poornima, is the full moon day in the month of Shravan. This day has a number of different names. Hayagriva Jayanti is also celebrated on Shravana Purnima. It is also known as Narali Purnima
Vat Purnima is celebrated on the full moon day of the month of Jyeshta. Women pray for their husbands by tying threads around a banyan tree (Vat) on this day. It honors Savitri, the legendary wife of Satyavan who escaped death for her husband's life. It is the chosen day for worshipping Yama deva
Guru Purnima, devotees offer puja (worship) to their Guru, on a full moon day. This is well known as Vyasa Purnima (Sanskrit. व्यास) after the birthday of the celebrated author of Mahabharata who is declared as the guru of all in the Shiva Purana.
Sharad Purnima or Kojagiri purnima, the Autumn Harvest Festival, on a full moon day.
Buddha Poornima, the day of birth, enlightenment and passing away of Gautama Buddha, on a full moon day.
Holi/Phalgun Purnima, the Spring Festival of Colours in Hinduism/Buddhism/Jainism, the full moon day in the month of Phalgun.
Dattātreya Jayanti is celebrated on the full moon day of the month of Margashira
Hanuman Jayanti is celebrated on the full mon of the lunar month Chaitra. However, this is celebrated on different days in different states. While Orissa celebrates this as Vaisakha Sankranti, Andhra Pradesh celebrates Vaisakha shukla paksha dashami, Kerala celebrates it in a previous month Margashira Amavasya coinciding with Mula Nakshatra. Chaitra Purnima is the chosen day for donation of rice to please Sri Chandra Deva, Moon god.
Shakambhari Purnima is celebrated on the full moon day of the month of Pausha
Madhu Purnima is celebrated on the full moon day of the month of Bhaadra. On this day Uma Maheswara Vrata as well as Shakra Vrata where Indra is worshiped for children and well-being.
Satyanarayan Puja vrata is observed on all full moon days
(Text) CC BY-SA