Sentence:  But every day after dinner, for an hour, we were all together, and then the Favourite and the rest of the Royal Hareem competed who should most beguile the leisure of the Serene Haroun reposing from the cares of State — which were generally, as in most affairs of State, of an arithmetical character, the Commander of the Faithful being a <WSD>fearful</WSD> boggler at a sum. 
Meaning of the word marked with <WSD> tags:  Terrible; shockingly bad.