This is the 138th most frequent Portuguese word.
dentro
Inside.
Here, 'dentro' is expressing an abstract concept, referring to something that exists internally within a person.
Dentro de cada pessoa existe um universo único.
Within each person, there is a unique universe.
In this sentence, the word 'dentro' is used as a preposition to denote the physical position of the cat being inside the box.
O gato está dentro da caixa.
The cat is inside the box.
In this context, 'dentro' describes an introspective perspective, indicating the internal mental space of the individual.