What does a "lost soul" mean?

a soul who turns there backs on God or doesn't know God is called a lost soul hope it helped

Anyone who is basically wandering aimlessly without purpose, one who does not have God.

a lost soul is someone who is in conflict with there own thoughts, and feelings about life. and why they are on earth in the first place. i believe that its someone who is searching for a purpose that they havent yet discovered. also it can be someone who hasnt yet experienced the grace and amor of the farther.