There are several synonyms for the phrase "impress upon," all of which involve conveying a message or idea with emphasis. One such synonym is "emphasize," which indicates the importance of a particular point or concept. Other synonyms include "stress," "highlight," "underscore," "reinforce," and "drive home." These words all convey a sense of urgency or significance, indicating that the speaker or writer wants to make sure the message is clearly understood. Whether speaking to an individual or a group, using these synonyms can help to convey the intended idea with greater impact and ensure that it is remembered long after the conversation or presentation has ended.