It is a misconception that the word "Hindu" is a deregotary term coined by Arabs. The word"Hindu" finds reference in our ancient literature too(it is said). It stands for "Heenani gunani dushayati iti Hindu" i.e. a Hindu is one who destroys the bad instincts within him on priority basis or a person who gives spiritual upliftment priority(over material progress). Thus the words "Christain" or a "Mohamadan" stand for "follower" of somebody but a Hindu is not one who follows anybody but one who is convinced of what to do and does it.
