After receiving his tenured position, he could finally focus on his research without worry.

tenured 是动词 tenure 的过去分词形式作形容词使用。tenure 源自拉丁语 tenere（持有），在学术领域特指"终身教职"，表示教授职位获得长期保障的状态。tenured position 即"终身职位"，通常指大学教师通过考核后获得的永久聘用资格。