adverb, descriptive · in a tight, fixed, or unyielding manner, typically referring to a physical grip or a gaze

他死死地攥着那张照片，不肯松手。

adverb · in an unwavering, unbendable, or rigid manner, often regarding persistence or adherence to a position

战士们死死守住阵地，打退了敌人的多次进攻。