lost 
(lôst, lŏst)
(lôst, lŏst)v.
Past tense and past participle of lose.
adj.
Idiom: 1. Unable to find one's way: a lost child.
2.
a. No longer in the possession, care, or control of someone or something: a lost pen.
b. No longer in existence; vanished or spent: lost youth.
c. No longer known or practiced: a lost art.
d. Beyond reach, communication, or influence: The expedition was lost to the world for two months.
3. Not used to one's benefit or advantage: a lost opportunity.
4. Having not been or unlikely to be won; unsuccessful: a lost battle; a lost cause.
5. Beyond recovery or redemption; fallen or destroyed: a lost soul.
6.
a. Completely involved or absorbed; rapt: lost in thought.
b. Bewildered or confused: I'm lost—can you start over?
be lost on
1. To have no effect or influence on: Her advice was lost on me.
2. To be beyond the comprehension of: The lecture was lost on us.