a murderer (especially one who kills a prominent political figure) who kills by a surprise attack and often is hired to do the deed
"his assassins were hunted down like animals"
"assassinators of kings and emperors"
a member of a secret order of Muslims (founded in the 12th century) who terrorized and killed Christian Crusaders
"The historical accounts describe how an assassin from the Nizari sect ambushed a Crusader lord during his journey through the Holy Land."
A member of the Nizari Ismaili Muslim community of the Alamut Period
"The historical novel vividly depicted the life of an assassin who served as a devoted member of the Nizari Ismaili Muslim community during the Alamut period."
To assassinate.
"The team planned to assassinate the corrupt official before he could flee the country."