Interpretant is a subject / sign that refers to the same object as another sign, transitively.[1]
[T]he interpretant is actually another sign referring to the same 'object.' Since any initial meaning can be re-interpreted (and often is), each interpretant is thus a sign leading to another interpretant, and so on ad infinitum. This double nature of the interpretant—as both the interpreted sign and the interpreting sign—confers unlimited regress or extrapolation in semiosis and led Pierce to conclude that man 'is the thought,' in fact, 'a sign himself' (5.314, 6.344). ... the sign [is] the fundamental vehicle connecting objects in the broadest sense and human reactions (interpretants).