ānantarya karma [ānantarika kamma] action with immediate destiny. The actions that follow retribution without delay are known as ānantaryāṇi karmāṇi. They are deadly sins; five heinous actions (Pañcānantaryāṇi karmāṇi), namely, killing of mother, father, or an Arhat; wounding a Buddha; and causing dissension in the Order of monks.

Buddhānusmṛti - A Glossary of Buddhist Terms

ānantarya-karma Sanskrit; Pāli, ānantariya-kamma). ‘Actions with immediate retribution’, the name given to five gravely wrong deeds that are said to result in rebirth in hell in the next life. They are parricide, matricide, killing an Arhat, wounding a Buddha, and causing a schism.

A Dictionary of Buddhism, Oxford University Press, 2003, 2004 (which is available in electronic version from answer.com)

ānantarya karma: (The five) mortal transgression: patricide, matricide, killing an arhat, causing aBuddha's bleeding and splitting of the Saṅgha. The term lit. means "immediate": These five are the gravest evil karma-s bringing immediate retribution in hell.

Sarvastivada Abhidharma, Sanskrit-English Glossary, by Bhikkhu KL Dhammajoti