"buksi" in Hungarian is an affectionate form of "head" - usually it's applied to smaller people (typically kids) and creatures with cute features (for example, a puppy or a kitten). This word is in addition to "fej", which is the regular word for "head".
"buksi" can also be used as an adjective, in front of "fej" (but not other nouns).
I feel that "head" just misses a lot of the additional meaning of the Hungarian word and I'm looking for a word (or phrase) that more closely matches. The best I can come up with is "cute little round head" but it feels long and complicated.