Sentence:  Even today range riders will come upon mummified bodies of men who attempted nothing more difficult than a twenty-mile hike and slowly <WSD>lost</WSD> direction , were tortured by the heat , driven mad by the constant and unfulfilled promise of the landscape , and who finally died . 
Meaning of the word marked with <WSD> tags:  fail to keep or to maintain; cease to have, either physically or in an abstract sense