There are several synonyms for "waits upon," including serve, attend, accommodate, assist, cater, and help. Each of these words conveys a similar meaning to "waits upon," indicating some form of aid or support. However, they can also differ slightly in nuance, emphasizing different aspects of the action being performed. For example, "serve" may imply a more subservient role, while "assist" suggests a more equitable relationship between the parties involved. Overall, the choice of synonym for "waits upon" will depend on the context and desired connotation, but all of these options can be useful alternatives.