This root form (lemma) is used in 3 different forms in the NT: Σεβαστοῦ (GMS), Σεβαστὸν (AMS), Σεβαστῆς (GFS).
It is glossed in 2 different ways: ‘of Augustus/(Sebastos)’, ‘Emperor’.
OET ACTS 25:21 Greek word=Σεβαστοῦ (Sebastou) Morphology=GMS English gloss=‘Emperor’ SR GNT ACTS 25:21 word 11
OET ACTS 25:25 Greek word=Σεβαστὸν (Sebaston) Morphology=AMS English gloss=‘Emperor’ SR GNT ACTS 25:25 word 19
OET ACTS 27:1 Greek word=Σεβαστῆς (Sebastaʸs) Morphology=GFS English gloss=‘of Augustus/(Sebastos)’ SR GNT ACTS 27:1 word 24