in·sep·a·ra·ble / inˈsep(ə)rəbəl/ • adj. unable to be separated or treated separately: research and higher education seem inseparable. ∎ (of one or more people) unwilling to be separated; usually seen together: they met 18 months ago and have been inseparable ever since. ∎ Gram. (of a prefix) not used as a separate word or (in German) not separated from the base verb when inflected.• n. a person or thing inseparable from another.DERIVATIVES: in·sep·a·ra·bil·i·ty / -ˌsep(ə)rəˈbilitē/ n.in·sep·a·ra·bly / -blē/ adv.