If we want to distinguish later selective processes from those which fortuitously happen to have latched onto a mutation first, we might call it secondary adaptation, or, to continue the proliferation of latinate terms ›exadaptation‹. [...] By introducing the notion of exadaptation we can allow that feathers have functions such as flight and thermo-regulation, even if they were originally selected for catching insects
Griffiths, P. (1992). Adaptive explanation and the concept of a vestige. In: Griffiths, P. (ed.). Trees of Life, 111-131: 118; 121.