"Not in it" is a commonly used phrase that means being excluded or not involved in a particular activity or situation. While the phrase itself is widely understood, there are several synonyms that can be used to convey the same meaning. Some effective substitutes include not included, left out, not considered, not involved, and outside the loop. These terms can be applied in various contexts such as social events, meetings, business deals, and other situations where someone is not included or part of a group. Using these synonyms can help to add variety to one's vocabulary while effectively conveying the intended message.