Inadequado vs. impróprio vs. inapropriado
While the Portuguese words "inadequado", "impróprio", and "inapropriado" are often interchangeable synonyms for "unsuitable", they carry distinct nuances. "Inadequado" usually refers to a lack of capacity or functional fit, "impróprio" often implies something is unsafe, forbidden, or naturally unfit for use, and "inapropriado" refers to breaking social norms or etiquette.
Inadequado
B1This word implies that something does not meet the specific requirements or standards of a situation. It suggests a functional mismatch, insufficiency, or that a chosen method will not work well for the desired goal.
O tamanho desta caixa é inadequado para o transporte da televisão.
(The size of this box is unsuitable for transporting the television.)
Eles usaram uma ferramenta inadequada e acabaram quebrando a peça.
(They used an unsuitable tool and ended up breaking the part.)
O médico considerou o tratamento inadequado para o paciente.
(The doctor considered the treatment unsuitable for the patient.)
Usar roupas de verão é inadequado para este clima frio.
(Wearing summer clothes is unsuitable for this cold weather.)
O tempo dado para a prova foi inadequado para a quantidade de questões.
(The time given for the exam was inadequate for the number of questions.)
Impróprio
B2This word often describes something that is unfit for consumption, usage, or is formally prohibited. It carries a stronger sense of being wrong by nature, unsafe, or going against specific regulations.
A prefeitura avisou que a água deste rio é imprópria para banho.
(The city hall warned that the water in this river is unfit for swimming.)
Este filme contém linguagem imprópria para menores de idade.
(This movie contains language unsuitable for minors.)
O alimento estava vencido e impróprio para consumo.
(The food was expired and unfit for consumption.)
O uso de celular é impróprio durante a decolagem do avião.
(Cell phone usage is improper during the plane's takeoff.)
Ele foi demitido por conduta imprópria no ambiente de trabalho.
(He was fired for improper conduct in the workplace.)
Inapropriado
B2This word is most commonly used in social contexts. It describes behavior, comments, or timing that is tactless, rude, or awkward given the specific social setting or audience.
Foi um momento inapropriado para contar aquela piada.
(It was an inappropriate moment to tell that joke.)
O comentário dele sobre o peso dela foi totalmente inapropriado.
(His comment about her weight was totally inappropriate.)
Ela sentiu que o presente era inapropriado para a ocasião.
(She felt the gift was inappropriate for the occasion.)
Rir durante o funeral seria considerado algo muito inapropriado.
(Laughing during the funeral would be considered something very inappropriate.)
A pergunta que o jornalista fez foi considerada inapropriada pelos políticos.
(The question the journalist asked was considered inappropriate by the politicians.)
Summary
To choose the best word, look at the context: use "inadequado" when something doesn't function well or meet a standard (insufficient); use "impróprio" for things that are physically unfit, unsafe to consume, or formally forbidden (improper); and use "inapropriado" for behaviors or actions that are socially awkward or rude (tactless).