Basanizō means to torment, torture, or cause severe distress. Appearing about 12 times in the NT, it derives from basanos (a touchstone for testing metals; torture). It is used of physical pain (Matthew 8:6 — the paralytic "terribly suffering"), demonic torment, the distress of the disciples in the storm (Matthew 14:24 — "buffeted"), and eschatological judgment (Revelation 14:10).
The presence of basanizō in the Gospels reveals the nature of the evil Jesus confronts. When demons encounter Jesus, they immediately cry out: "Have you come to torment [basanisai] us before the appointed time?" (Matthew 8:29) — recognizing His authority to judge and end their power. Jesus' ministry is a pattern of reversing basanismos: the suffering one is healed, the demonized is liberated. In Revelation, the bowls of wrath involve basanismos — the God who forbore judgment now vindicates His creation. He who was tormented for us (Isaiah 53) becomes the one before whom tormentors flee.