/ ˌslaʊ əv dɪˈspɒnd; NAmE dɪˈspɑːnd/ noun
[ sing. ] a mental state in which a person feels no hope and is very afraid :
He was sinking into the Slough of Despond.
ORIGIN: From the name of a place that Christian, the main character, must travel through in John Bunyan's The Pilgrim's Progress .