The phrase "free as a bird" is often used to express a feeling of liberation and joy. However, there are several synonyms that can be used to convey similar emotions. "Unfettered" is one such word, which means free from restrictions or limitations. "Liberated" also connotes a sense of freedom, as does "unrestricted" or "unencumbered". "Unrestrained" and "unbound" also have similar connotations, as does "unshackled". "Independent" can also be used to describe this feeling of freedom, as can "autonomous" or "self-governed". Each of these synonyms can be used to express the sense of liberation and joy that comes with feeling free as a bird.