People view the "Soul" in many different ways. I have heard it referenced as to emotions, feelings, etc.. Then I have heard it referenced as unto a humans spirit being. I myself view it as our emotions and feelings. I believe that we as humans are made up of 3 different components : Body, Soul, Spirit. So in my opinion to lose your soul would mean to be without feelings and emotions. To be merely a shell without emotions.
A human soul is a God given gift that cannot be destroyed, and therefore there is never no true death for our souls. The only way we can truly lose our soul, is to burn in hell. There our soul is lost forever, and has no meaning at all. Without God, Who is LIFE, present in our soul, our soul experiences a spiritual death. A Scripture that comes to mind is Jesus' parable of He being the true Vine and we (the souls) being the branches attached to the true Vine. (John 15:5). Jesus is the source of life, and unless we are attached to Him our soul has no life. Thus, our soul does not experience salvation. So salvation is an on-going process to a Catholic and not just a one time deal. A soul has to be open to God on a daily basis and throughout our Christian's life and journey on earth.