The Greek noun anesis means rest, relief, relaxation, or freedom from constraint. Occurring 5 times in the NT, it describes relief from affliction (2 Corinthians 2:13; 7:5; 8:13), comfort for prisoners (Acts 24:23), and future relief from persecution (2 Thessalonians 1:7).
Anesis carries both present and eschatological dimensions. Paul speaks of having no anesis (no relief) in his spirit while anxiously waiting for news from Corinth (2 Corinthians 2:13) — showing how deeply he cared. Acts 24:23 uses it of human generosity: Felix granted Paul anesis (freedom to have his friends attend him). But the most significant use is 2 Thessalonians 1:7: God will give persecuted believers anesis when Christ returns. Eternal relief from suffering is guaranteed — the present groaning will give way to glorious rest.