1. (adjective) Not valid; lacking legal or binding force
The contract was declared invalid by the court.
O contrato foi declarado inválido pelo tribunal.
2. (adjective) Not sound; based on false reasoning or faulty logic
That argument is invalid and does not support your conclusion.
Esse argumento é inválido e não sustenta sua conclusão.
3. (noun) A person who is chronically ill, disabled, or infirm
The nurse cared for the invalid with great patience.
A enfermeira cuidava do inválido com muita paciência.