What does "lost" mean?

Additional senses

1. 2.Not employed or enjoyed; thrown away; employed ineffectually; wasted; squandered; as, a lost day; a lost opportunity or benefit.
2. 3.Having wandered from, or unable to find, the way; bewildered; perplexed; as, a child lost in the woods; a stranger lost in London.
3. 4.Ruined or destroyed, either physically or morally; past help or hope; as, a ship lost at sea; a woman lost to virtue; a lost soul.
4. 5.Hardened beyond sensibility or recovery; alienated; insensible; as, lost to shame; lost to all sense of honor.
5. 6.Not perceptible to the senses; no longer visible; as, an island lost in a fog; a person lost in a crowd.
6. 7.Occupied with, or under the influence of, something, so as to be insensible of external things; as, to be lost in thought. Lost motion (Mach.), the difference between the motion of a driver and that of a follower, due to the yielding of parts or looseness of joints.