This is the 663rd most frequent Croatian word.
velikog
"Velikog" means "of the big" or "of the great" (genitive singular form).
Here, 'velikog' is an adjective in the genitive singular masculine form, referring to 'artist' ('umjetnika') and indicating his greatness in terms of achievement or stature.
U parku stoji spomenik velikog umjetnika.
In the park stands a monument of a great artist.
The word 'velikog' is used here as an adjective in the genitive singular masculine form to describe the size of 'heart' ('srca').
Imam psa velikog srca.
I have a dog with a big heart.
In this sentence, 'velikog' is an adjective in the genitive singular masculine form, qualifying 'bear' ('medvjeda'), referring to its size.