There are many synonyms for the phrase "look down upon." Some examples include: despise, disdain, revile, snub, belittle, scorn, and undervalue. These words all suggest a sense of superiority and contempt towards someone or something. Additionally, phrases like "turn up one's nose at" and "look down one's nose at" convey a similar connotation of disgust and disdain. It is important to note that using these words and phrases in conversation or writing can come across as rude and insensitive, so it is important to use them judiciously and with care.