/ ɪgˈzɔːstʃən; NAmE / noun [ U ]
1.
the state of being very tired :
suffering from physical / mental / nervous exhaustion
Her face was grey with exhaustion.
2.
( formal ) the act of using sth until it is completely finished :
the exhaustion of natural resources
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WORD ORIGIN
early 17th cent.: from late Latin exhaustio(n-) , from Latin exhaurire drain out, from ex- out + haurire draw (water), drain.