There are several synonyms for the phrase "not very" that one can use to express mild negativity or lack of enthusiasm. One possible alternative phrase is "somewhat," which indicates a moderate level of intensity. Another option is "slightly," which implies a minor degree of something. "Rather" is also a suitable synonym that denotes to a considerable extent or degree. Similarly, one can use the words "moderately," "fairly," and "reasonably" to convey a middling level of something. Other alternatives may include "mildly," "marginally," and "minimally." Using synonyms for the phrase "not very" can help to add nuance, clarity, and creativity to one's writing and speech.