There are several synonyms for the phrase "loose off," which generally means to loosen or undo something. One common synonym is "unfasten," which can refer to anything from untying a knot to unbuckling a belt. Another similar term is "release," which often implies a deliberate action to free something from confinement, such as releasing a latch or a catch. Other synonyms include "untether," "unleash," "unbolt," and "undo." All of these terms share a sense of letting go or freeing something, and can be used in a variety of contexts, from unchaining a prisoner to unhooking a fish from a line.