From peri (over) and kratos (strength/power). Having mastery over, being in control of. Used in Acts 27:16 of barely being able to secure the lifeboat during a storm.
During the shipwreck in Acts 27, the sailors could barely gain control of the lifeboat (Acts 27:16). This vivid detail illustrates that in life's storms, human control is fragile. Only God maintains sovereign control when human strength fails.