scis·sion \ˈsizhən, -ish-\noun (-s) Etymology: French, from Late Latin scission-, scissio, from scissus (past participle of scindere to split) + -ion-, -io -ion 1.: a division or split in a group or union : a state of dissension : schism 2. a.: an act of cutting, dividing, or splitting or the state of being cut, divided, or split : division b.: cleavage 5 < cracking or carbon-carbon scission >