Ānantarika karma (Sanskrit) or Ānantarika kamma (Pāli) are the most serious offences in Buddhism that, at death, through the overwhelming karmic strength of any single one of them, bring immediate disaster. Both Buddhists and non-Buddhists must avoid them at all costs. Such offenses prevent perpetrators from attaining any of the stages of enlightenment and from ordaining into the Sangha. Those who have committed any of the five acts of Ānantarika kamma are said to be reborn in the naraka of Avīci, the very lowest of all the Hells of Buddhism. The Ānantarika kamma are:Triplegem glossary
Killing one's mother (matricide) Killing one's father (patricide) Killing an Arahant Wounding a Tathāgata Creating division in the Sangha
Etymology
Ānantarika derives from na, an, and antara.
An in this context refers to the "seed" of karma and antara means in storage, or waiting to germinate or bear fruit. These two words combined create anantara, which means a karma seed waiting to germinate. Na means "not", and therefore, ānantarika means "not stored to germinate/mature" or "brings vipāka (karmic consequence) immediately", leading to rebirth in hell.
Ānantarika kamma in Mahayana Buddhism Amitabha Buddha, one of the primary buddhas in Mahayana and the most widely-worshipped Buddhist deity in East Asian BuddhismWilliams (2008), p. 238. discusses the Ānantarika kamma in his Original Vow. His vow reads:
See also Ajatashatru Avijjā Buddhist views on sin Devadatta Icchantika Karma in Buddhism Merit (Buddhism) Moha (Buddhism) Pratitya-samutpada Samsara (Buddhism) Three Poisons Twelve Nidanas
References
Further reading Silk, Jonathan A. (2007). Good and Evil in Indian Buddhism: The Five Sins of Immediate Retribution, Journal of Indian Philosophy 35 (3), 253–286