1 a: a number of shots fired simultaneously or in rapid succession b: something that gives the effect of a fusillade <a fusillade of rocks and bottles>2: a spirited outburst especially of criticism
The word fusillade is a noun, a singular, common noun. A fusillade is a series of shots fired simultaneously or in quick succession or something that gives the effect of a fusillade.
A fusillade is a burst of gunfire (from the French fusil, a rifle). Merciless means without mercy. So a merciless fusillade is a burst of gunfire without mercy. Clearly there is some metonymy (It is...