This root form (lemma) is used in 3 different forms in the NT: συνήθεια (NFS), συνήθειαν (AFS), συνηθείᾳ (DFS).
It is glossed in 3 different ways: ‘a custom’, ‘by custom’, ‘custom’.
OET JOHN 18:39 Greek word=συνήθεια (sunaʸtheia) Morphology=NFS English gloss=‘a custom’ SR GNT JOHN 18:39 word 3
OET 1COR 8:7 Greek word=συνηθείᾳ (sunaʸtheia) Morphology=DFS English gloss=‘by custom’ SR GNT 1COR 8:7 word 10
OET 1COR 11:16 Greek word=συνήθειαν (sunaʸtheian) Morphology=AFS English gloss=‘custom’ SR GNT 1COR 11:16 word 9