This is the 9429th most frequent Polish word.
wspaniałego
"Wonderful" or "great."
The word "wspaniałego" is "wonderful" in a masculine singular genitive form, used here due to the preposition "w" governing the genitive case.
To był naprawdę wspaniałego wieczoru.
It was truly a wonderful evening.
In this sentence, "wspaniałego" refers to "wonderful" in a masculine singular genitive form, aligning with the grammatical structure of "życzyć," which requires the genitive case.
Życzę ci wspaniałego dnia.
I wish you a wonderful day.
Here, "wspaniałego" modifies "wynalazku" (invention), which is in the genitive case because of its role in the possessive construction with "przykład."