A "unique nickname" refers to a special and one-of-a-kind name that is given to someone as an alternate way of referring to them. It is different from their real or usual name and helps to distinguish them from others. Full definition
Use your own unique nickname instead of a long and complicated default wallet address to conveniently transfer or exchange ICX. (icon.foundation)
Use your own unique nickname instead of a long and complicated default wallet address to conveniently transfer or exchange ICX. (icon.foundation)
Hi Ridhima, Please check this post: Nicknames for Babies (Also some tips given at the end of post in link about creating unique nicknames) (gomama247.com)