ninja

Noun ninja has 2 senses

• ninja(n = noun.person) - a member of the ninja who were trained in martial arts and hired for espionage or sabotage or assassinations; a person skilled in ninjutsu;
is a member of ninja
is a kind of mercenary, soldier of fortune

• ninja(n = noun.group) - a class of 14th century Japanese who were trained in martial arts and were hired for espionage and assassinations;
is a kind of class, social class, socio-economic class, stratum