The phrase "letted loose" implies a sense of release or relaxation, which can be conveyed through a number of synonyms. One option is "unleashed," which suggests a sudden and forceful burst of energy or emotions. Another option is "liberated," which connotes a sense of freedom from constraints or limitations. "Set free" is another similar phrase, which suggests a deliberate or intentional act of allowing something or someone to move or act without hindrance. Other synonyms might include "released," "turned loose," or "allowed to roam," depending on the context and the specific connotations desired.