A fusilier was a soldier who carried a fusil — a light flintlock musket. The word belongs to European armies from about the seventeenth century on. In British history, Fusiliers became the name of certain infantry regiments, and some of those names are still used today, even though the men no longer carry muskets. So you will meet fusilier as a kind of soldier in old battles, and Fusilier as a regiment name in later news. It is a historical and military word, not everyday English. Though actually, at first a fusilier was picked out because his gun was lighter than the old heavy musket; later the name stuck to whole units, long after the weapon had changed.

燧發槍兵、火槍兵（舊時步兵；英國某些團名至今仍叫 Fusiliers）