Sentence:  Fear, the product of guilt, is a true night-plant. Like some of those gigantic fungi the botanists tell of, it springs up in the dark, and in an hour of restless tossing, sudorific, <WSD>horripilating</WSD> wretchedness, canopies our bed with a phantom toad-stool of gigantic size. The load that the conscience can jauntily stagger under in the broad light of day, ... will, in the gloom and silence of the night, wear its bearer to his knees. 
Meaning of the word marked with <WSD> tags:  Horrendous, horrifying, terrifying.