Opiso (ὀπίσω) means behind, after, or following — indicating position or direction in the wake of something or someone. It is the word used in Jesus' call to discipleship: 'Follow opiso me' — literally, 'come after me.' It also appears in warnings about looking back (opiso) and in Revelation's four living creatures crying 'Holy' day and night without turning back.
'Come after me' (opiso) is the foundational call of discipleship. It is a spatial metaphor: Jesus is walking ahead, and disciples are behind, following in His wake. The disciple's position is always opiso — not beside, not in front, but following. Jesus' rebuke of Peter — 'Get behind me, Satan' (opiso mou) — uses the same word: there is only one place for Peter, and it is behind Jesus, not standing in His way.
The geometry of discipleship is opiso: behind the Master, in the dust of His feet (as the rabbinical expression goes), walking where He walked, touching what He touched. This posture is both humility and honor. The disciple is not dragged but follows willingly. Luke 9:62 warns that looking back (opiso) while plowing makes straight furrows impossible — discipleship requires forward eyes and a forward heart.