Tenacity

Tenacity is a League of Legends stat that reduces the duration of crowd-control effects such as stuns, slows, roots, and silences. At 30% tenacity, a two-second stun is cut to 1.4 seconds, which can be the difference between dying and surviving a fight.

It does not stop crowd control, only shortens it, and most sources of tenacity do not stack additively in a simple way. Players access it through certain boots, runes, and items, and it is especially prized by melee fighters and tanks who must dive into the enemy team and stay functional under heavy lockdown.