Sentence:  They had lunch at a sidewalk cafe overlooking the intersection of two broad , busy , unpicturesque streets , and coming home they got <WSD>lost</WSD> in the Metro ; it took them over an hour to get back to the station where they should have changed , in order to take the line that went to the Place Redoute . 
Meaning of the word marked with <WSD> tags:  incapable of being recovered or regained