Sentence:  Even among friends at the dinner-table he talked as though he were denouncing them, or someone else, on a platform; he measured his phrases, built his sentences, cumulated his effects, and pounded his opponents, real or imagined. His humor was glow, like iron at dull heat; his blow was elementary, like the <WSD>thrash</WSD> of a whale. 
Meaning of the word marked with <WSD> tags:  A beat or blow; the sound of beating.