A systemic vulnerability of the Border Gateway Protocol routing system, known as 'route leaks', has received significant attention in recent years. Frequent incidents that result in significant disruptions to Internet routing are labeled "route leaks", but to date we have lacked a common definition of the term. In this document, we provide a working definition of route leaks, keeping in mind the real occurrences that have received significant attention. Further, we attempt to enumerate (though not exhaustively) different types of route leaks based on observed events on the Internet. We aim to provide a taxonomy that covers several forms of route leaks that have been observed and are of concern to Internet user community as well as the network operator community.