Upākarma "Beginning" (Sanskrit: उपाकर्म), also called Āvaṇi Aviṭṭam (Tamil: ஆவணி அவிட்டம்), Janivārada Huṇṇime (Kannada: ಜನಿವಾರದ ಹುಣ್ಣಿಮೆ),Gahmā Pūrṇimā (Odia: ଗହ୍ମା ପୂର୍ଣିମା), Jaṁdhyāla Paurṇami (Telugu: జంధ్యాల పౌర్ణమి) is a Vedic ritual practiced by Hindus of the Brahmin caste. This ritual is also practiced by the Kshatriya and Vaishya community, who are dvijas and therefore have the rights to do Sandhyavandanam, the daily ablution ritual.
Upākarma is conducted once a year during the shravana or Dhaniṣṭhā nakṣatra of the Hindu calendrical month Śrāvana, when Brahmins ritually change their upanayana thread accompanied by relevant śrauta rituals, making śrāddha offerings to the rishis, whom Hindus believe composed the Vedic hymns. The day, also called Śrāvana Pūrnima "Full Moon of Śrāvana" in other parts of India, usually occurs the day after the Śravana nákṣatra, which also marks the Onam festival of Kerala.
Brahmins belonging to the Samaveda do not perform upakarma rituals or change their thread on this day but rather on Bhādrapada tritiya, the third day of the month Bhādrapada with Hastaa nakshatra. Shukla Yajurvedic Brahmins of North India and Odisha do upakarma the previous day if the full moon spans two days.