lost (from misplaced ) 1 Missing participle. adj Lost. ( To be ) It is said of the one who does not know where he is, what path he has to follow to go to his house or another place, etc .: A lost child . Lost by someone: Department of lost objects on public roads . 2 Applied to road, place or a place name, removed; outside of the frequented roads. 3 Applied to eyes, gaze or sight , not fixed in a thing as when one looks normally, but as fixed in something distant or invisible, or wandering in all directions and with an expression of terror. Lost.