Whats the gramatical term...need an answer FAST!!!!?

Question

for an object that has 2 or more different names but means the same thing, and it depends on where you live as to which term you use

ex: soda and pop, hair tie and ponytail and hair binder, rubber band and gum band, shopping cart and buggy etc...

thank you! its driving me and my friend NUTS!

Answer 1

All I can think of is 'colloquialisms', but I am uncertain

Answer 2

Synonyms?

Answer 3

Dialectal synonyms