There are numerous synonyms for the phrase "be bound up/together". Some of the common ones include interlocked, interconnected, intertwined, entwined, knotted, tangled, enmeshed, and meshed. These synonyms carry the same idea of two or more things being tightly connected, whether physically or conceptually. For instance, two trees growing close together can be interlocked or intertwined. Similarly, a person's thoughts and emotions can become enmeshed or tangled. In all cases, the phrase "be bound up/together" is used to describe a relationship that cannot be easily separated. Overall, having a good understanding of these synonyms can help you to communicate more clearly and effectively.