The boss tried to cow the employees into working overtime with his stern look.

cow 在这里是动词，本义是"奶牛"，作为动词时引申为"恐吓、胁迫"，因为奶牛常被人类驱使和控制。这个用法形象地描述了用威吓手段迫使他人服从的行为。