This is the 954th most frequent Portuguese word.
século
The Portuguese word "século" means "century" in English.
In this sentence, 'século' refers to a period of one hundred years, specifically in counting historical time periods.
Estamos no século XXI.
We are in the 21st century.
Here, 'século' is again used to denote a century but now tied to historical reference of specific events within that century.
Durante o século XVI, muita coisa mudou na Europa.
During the 16th century, many things changed in Europe.
In this context, 'século' refers to a future span of one hundred years starting from a given reference point in time, projecting forward.