kilon.

kilokilo: [19] Khílioi was Greek for a ‘thousand’. It was adopted in French in the 1790s as the prefix for ‘thousand’ in expressions of quantity under the new metric system, and various compound forms (kilogram, kilolitre, kilometre, etc) began to find their way into English from the first decade of the 19th century onwards. The first recorded instance of kilo being used in English for kilogram dates from 1870.kilo (n.)1870, shortening of kilogram. Slang shortening key (in drug trafficking) is attested from 1968.