The teacher gave a sharp rebuke to the students who played with their phones in class.

rebuke 是名词，意思是"严厉的批评、指责"。这个词带有正式和严肃的语气，通常用于上级对下级或权威人士对不当行为的正式谴责。rebuke 也可以作动词用，表示"斥责、训斥"的意思。