Subtropical cyclone
During the 1950s and 60s, subtropical cyclones were simply called "semi-tropical". There was much discussion between meteorologists in the late 1960s as to what a subtropical cyclone was. So, in 1972, the National Hurricane Center (NHC) officially classified the type under a new category different from actual tropical cyclones. During the 1970s, the NHC began making a new list of names, separate for subtropical cyclones, although that process was soon canceled because it was rejected by many scientists.  After that, subtropical storms were just numbered, such as Hurricane Karen from 2001, which was originally named Subtropical Storm One.  But in 2002, a policy change had tropical and subtropical storms share the same list of names for the whole season, which started with Subtropical Storm Nicole in 2004.