This root form (lemma) is used in 2 different forms in the NT: ἀθέτησιν (AFS), ἀθέτησις (NFS).
It is glossed in 2 different ways: ‘an annulment’, ‘the annulment’.
OET HEB 7:18 Greek word=ἀθέτησις (athetaʸsis) Morphology=NFS English gloss=‘an annulment’ SR GNT HEB 7:18 word 1
OET HEB 9:26 Greek word=ἀθέτησιν (athetaʸsin) Morphology=AFS English gloss=‘the annulment’ SR GNT HEB 9:26 word 18