Noun
Formerly, a member of an independent body of marksmen in the French army. They were used sometimes in front of the army to annoy the enemy, sometimes in the rear to check his pursuit. The term is now applied to all troops acting as skirmishers.
Source: Webster's dictionaryIn addition, four mixed zouave and tirailleur regiments (régiments mixtes de zouaves et tirailleurs) were raised for the First World War, all of which were redesignated Algerian tirailleur regiments in 1918 or 1920. Source: Internet