'assassinate' originates from French 'assassiner' (to murder), which comes from Italian 'assassinare' and ultimately from Arabic 'ḥashshāshīn' (the plural of 'ḥashshāsh', 'hashish-user').

'assassinate' entered English via Middle French/Italian forms derived from Arabic 'ḥashshāshīn'; the English verb was formed in the 16th century from these Romance-language sources and the suffix -ate (from Latin/vernacular verb formation).

Initially associated with the group called the 'Hashshashin' (and by implication 'users of hashish'), it came to mean the targeted murder of prominent figures and now means deliberately killing a prominent person for political or other motives.