The Proto-Indo-European word *koro-
Word *koro-
Meaning war
See also Linear B: ko-ru ‘helmet’
Cappadocian Greek: χερέκι ‘soldier, fighter’

Other words that might be of interest
*ghostis ‘enemy, stranger, guest’, *k̂at- ‘battle’, *des- ‘enemy’, *skolmehₐ ‘sword’