1. Parted with unwillingly or unintentionally; not to be found; missing; as, a lost book or sheep.
2. Parted with; no longer held or possessed; as, a lost limb; lost honor.
3. Not employed or enjoyed; thrown away; employed ineffectually; wasted; squandered; as, a lost day; a lost opportunity or benefit.
5. Having wandered from, or unable to find, the way; bewildered; perplexed; as, a child lost in the woods; a stranger lost in london.
6. 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.
7. Hardened beyond sensibility or recovery; alienated; insensible; as, lost to shame; lost to all sense of honor.
8. Not perceptible to the senses; no longer visible; as, an island lost in a fog; a person lost in a crowd.
9. Occupied with, or under the influence of, something, so as to be insensible of external things; as, to be lost in thought.
(Science: machinery) lost motion, the difference between the motion of a driver and that of a follower, due to the yielding of parts or looseness of joints.
Origin: prop. P. P. Of oe. Losien. See lose.