This is the 10390th most frequent Polish word.
cudownym
"Wonderful" or "miraculous."
In this sentence, 'cudownym' is used as an instrumental singular masculine adjective to describe the noun 'dniem' (day).
To był cudownym dniem dla nas wszystkich.
It was a wonderful day for all of us.
Here, 'cudownym' is employed as an instrumental singular neuter adjective modifying 'doświadczeniem' (experience).
Spacer po lesie był cudownym doświadczeniem.
Walking in the forest was a wonderful experience.
In this instance, 'cudownym' serves as an instrumental singular masculine adjective pertaining to 'darem' (gift).