Sentence:  Long after his cigar burnt <WSD>bitter</WSD>, he sat with eyes fixed on the blaze. When the flames at last began to flicker and subside, his lids fluttered, then drooped; but he had lost all reckoning of time when he opened them again to find Miss Erroll in furs and ball-gown kneeling on the hearthnb.... 
Meaning of the word marked with <WSD> tags:  Having an acrid taste (usually from a basic substance).