This was once to be a part of something that now is not and never shall be. I guess I'll just throw it here.

Throughout pony history, the mark a pony wears to represent their magically-affirmed talents has gone by many different names. The general consensus for the mark is currently ‘cutie mark’ and has been so for several generations. The term originally arose during the Pastel Revolution¹ cirra. 963 C.E. as a response to a perceived threat by surrounding nations of an impending pony hegemony². The term has been in use long enough that many of today’s youth and young adults aren’t aware that the term is a modern invention, despite the fact that many ponies born before 1960 still use the older term ‘Sigil’. Slang among city youth today prefers the shortened term ‘Mark’, and this formulation is becoming increasingly popular outside of the circles it was formed in, although it’s use is currently still limited to the large multi-tribe cities such as Manehattan and Detrot. If previous trends follow, the term has an approximately one-in-two chance of supplanting ‘cutie mark’ within the next 8-12 years. The specific term used in biological and thaumatological settings is Ingenii Signum, Old Whinny for ‘talent mark’, although the term sees almost no use outside of this setting.

¹ The Pastel Revolution is the term for the counterculture that arose in the 960s in response to the patriotism and militarism of the 950s, itself a response to Equestrian involvement in the Griffon-Cretan War in the 1940s. The Pastel Revolution and it’s adherents, the ‘flower children’, attempted to reaffirm ponykind’s status as peace-loving, harmless herbivores through non-threatening terms and imagery. The counterculture became the dominant cultural force in Equestria throughout the 970s, and, although the population has largely moved on in the intervening years, pastels and lighter colors are still the dominant color in most pony fashion and architecture, and many terms coined during the period are still in regular use.

² Such scares occur with clockwork regularity two or three times a century. Few of the frightened minotaurs and griffons bother to remember that Equestria’s borders have not changed in near on a millennia.

Weighted Ink, “What Words There Were: An Etymological Encyclopedia”, 995 C.E.