to bring someone safely through a threat into wholeness: to rescue, heal, or save
At its core this word means to carry a person safely through something that would otherwise destroy them, and leave them whole on the other side. The threat can be a storm, a sword, a disease, or finally death and judgment itself, and the wholeness can be a body that works again, a life spared, or a person made right with God forever.
Because one verb covers all of that, the Bible can let one rescue stand for another. When Jesus tells a healed woman that her faith has saved her, the same words that mean her body is well also point past her body to something larger. The Gospels keep that double ring on purpose, so a reader should hear the everyday sense and the deeper one at once rather than forcing the word into only one of them.
In the letters, especially Paul's, the word settles most often on the largest threat of all, being lost before God. There it names being brought safe through judgment into lasting life with him. The senses below are not separate words but one rescue seen at different depths, from a sinking boat to the day of judgment.