Mount Sipylus
The origin of the family's surname, to follow Donald Nicol, "lies between romantic guesswork and philological conjecture." Prince Michael Cantacuzino, an 18th-century Romanian aristocrat of the Cantacuzino family who traced his ancestry to this Byzantine family, provides examples of the first kind, such as the family began with a certain "Lucie Cusin" who married one "Serafina Catina", and united their familial names into the compound one of "Ca(n)tacuzino". Nicol prefers the second kind of explanation, and repeats the theory of Konstantinos Amantos that Kantakouzenos derives from , ultimately from the locality of Kouzenas, a name for the southern part of Mount Sipylus near Smyrna. Nicol lists some connections the Kantakouzenos had with the locale in the 11th and 13th centuries.