Definition - What does Purnima mean?
Purnima is a Sanskrit term meaning "full moon," and referring to the day of the month when a full moon is first present.
This is also the division between Shukla Paksha (the bright two weeks before Purnima) and Krishna Paksha (the dark two-week period after it).
Yogapedia explains Purnima
Purnima is a time when many festivals are celebrated across Asia. Kartik Poornima, Vat Purnima, Guru Purnima and Buddha Poornima are a few of the most widely celebrated of these full moon festivals.
Buddha Poornima is especially significant for Buddhists as this is the celebration of Buddha’s birth, enlightenment and death. These events are said to have occurred under the full moon in May, which is when the festival takes place.
Purnima is also commonly used as a girl’s name in the Indian subcontinent.