Dictionary definitions:
Parinibbāna: ‘full Nibbāna’, is a synonym for Nibbāna; this term, therefore, does not refer exclusively to the extinction of the 5 groups of existence at the death of the Holy One, though often applied to it.
[…]
The full extinction of the groups of existence (khandha-parinibbāna), also called an-upādi-sesa-nibbāna (s. It. 41, A. IV, 118), i.e. ‘Nibbāna without the groups remaining’, in other words, the coming to rest, or rather the ‘no-more-continuing’ of this physico-mental process of existence. This takes place at the death of the Arahat."—Nyanatiloka