Five rebellious acts or sins

 
five rebellious acts or sins (五逆).
These are
(1) patricide,
(2) matricide,
(3) killing an Arhat,
(4) shedding the blood of a Buddha (including maligning His Dharma), and
(5) destroying the harmony of a Saṅgha.

They are also called the karma of the five no interruptions because any of them drives one into Avīci Hell, the hell of the five no interruptions.

Source

www.sutrasmantras.info