Gallowglass is an old Irish term that means foreign warrior. However, there are several synonyms that can be used to describe this term. One such synonym is mercenary, which implies someone who fights for money. Another possible synonym is hired gun, which suggests a hired assassin. Other possible synonyms for gallowglass include soldier of fortune, hired soldier, and professional warrior. These terms all imply a skilled fighter who is being paid to fight for a particular cause or individual, usually in a foreign land. The use of these synonyms can help to add color and depth to writing that involves ancient warriors and battles.