^Boyle's Persian-English dictionary indicates that the suffix -koš[koʃ] is the present stem of the verb 'to kill' (koštanکشتن). According to linguist Francis Joseph Steingass, the suffix -kush means 'a male; (imp. of kushtan in comp.) a killer, who kills, slays, murders, oppresses as azhdaha-kush.'
^Boyle, J.A. A Practical Dictionary of the Persian Language. Luzac & Co. 1949: 129.
^Francis Joseph Steingass. A Comprehensive Persian-English Dictionary. Asian Educational Services. 1992: 1030–1031 (kush means "killer, kills, slays, murders, oppresses"), p. 455 (khirs–kush means "bear killer"), p. 734 (shutur–kush means "camel butcher"), p. 1213 (mardum–kush means "man slaughter"). ISBN 978-81-206-0670-8.