This is the 4931st most frequent Portuguese word.
idade
Age.
Here, 'idade' refers to the concept of a person's age in numerical terms.
A idade é apenas um número.
Age is just a number.
'Idade' here specifies a legal or required age for an activity, such as driving.
Eu alcancei a idade mínima para dirigir.
I reached the minimum age to drive.
In this sentence, 'idade' is part of a compound noun describing a historical period ('Middle Ages').