A notion that emerged in biology, thrived in postcolonial theory, then entered media studies as it metastasized throughout the humanities and social sciences, hybridity is emblematic of our era. Used to describe mixtures of cultures, races, languages, systems, even paradigms, hybridity emerged in the 1990s as a master trope, a necessary heuristic device to understand a world in flux. As of this writing, the heyday of hybridity— when it animated entire subfields and spawned heated arguments between celebrants and critics—is behind us. Now largely absent from book titles, conference themes, and intellectual polemics, hybridity has taken residence in interdisciplinary venues like media studies, as a once-dominant concept now content with latent taken-for-granted-ness and banal usage. We now assume, rather than argue over, hybridity. The notion of hybridity developed in the study of genetic variability. The word entered the English language in the late 1830s, and half a century later it had made the leap from biology to culture, when the _Oxford English Dictionary_ in 1890 used hybridity to compare linguistic to racial mixture. Synonyms of hybridity were in circulation much earlier. Both _métissage_ (French) and _mestizaje_ (Spanish) harken back to the Latin _miscere_, “to mix.” In the twelfth century, Old...