What is "harquebusier"

The harquebusier was the most common form of cavalry found throughout Western Europe during the early and mid 17th century. Early harquebusiers were characterised by the use of a form of carbine, called a "harquebus". In England, harquebusier was the technical name for this type of cavalry, though in everyday usage they were usually simply called 'cavalry' or 'horse'. In Germany they were often termed ringerpferd, or sometimes reiter, in Sweden they were called lätta ryttare.