There are several synonyms for the phrase "chain together" that can be used when referring to connecting or linking things together. Some of these include "string together," "concatenate," "link," "connect," and "couple." Each of these synonyms can be used in different contexts depending on the situation. For example, "string together" or "concatenate" may be used when referring to a chain of words or phrases in a sentence, while "link" or "connect" can be applied when referring to physical objects that are connected together. "Couple" can refer to connecting two things that work together, or two people who are a couple in a relationship. Overall, these synonyms provide a variety of alternatives when trying to convey the idea of connecting or linking things together.