This is the 566th most frequent Portuguese word.
gustavo
"**Gustavo**" is a proper noun, typically a Portuguese male given name, equivalent to "Gustav" or "Gustavo" in English.
In this sentence, 'Gustavo' is used as a proper noun, representing a person's name.
Gustavo foi à escola pela manhã.
Gustavo went to school in the morning.
Here, 'gustavo' is used as an adjective, derived from a proper noun, to describe a specific style or attribute.
O trabalho gustavo do artista impressionou a todos.
The gustavian work of the artist impressed everyone.
In this case, 'Gustavo' is again a proper noun used directly in addressing someone.