Origin: Greek prefix syn-
Synonymous has 2 different meanings across 1 category:
(of words) meaning the same or nearly the same
"In many dictionaries, the terms "happy" and "contented" are listed as synonymous because they often convey similar feelings of satisfaction."
having an identical meaning
"The terms "ATM" and "cash machine" are synonymous in everyday conversation because they refer to the exact same device."