H8307. sheriruth
שְׁרִירוּת, usually שְׁרִרות noun feminine firmness, always = stubbornness; only construct ׳שׁ, followed by ׃לֵב : [Jer 9:13]; [13:10]; [23:17]; [Deut 29:18]; [Psa 81:13] (שְׁרִירוּת); ׳שׁ הָרָע ם לִָ [Jer 3:17]; [7:24]; [11:8] (׳שְׁרִי), so (לִבּוֺ) [16:12]; [18:12].