Even though it sounds like a made-up word, splendiferous is a word for wonderful things. You may have seen a splendiferous sunset or a splendiferous velvet gown in your day.
A splendor is a beautiful sight. Splendiferous things are even better: this somewhat silly-sounding word is a term for praising things that are absolutely fantastic, either because they're beautiful or otherwise great. A gorgeous spring day is splendiferous. A delicious dinner is splendiferous. Seeing a friend for the first time in months is splendiferous. As long as you're referring to something great, it could be called splendiferous.