Interferir vs. intrometer-se
While both interferir and intrometer-se can translate to "to interfere" in English, they describe different types of actions. Interferir usually refers to disrupting a process, outcome, or function (often objective), whereas intrometer-se refers to meddling in personal affairs or entering uninvited into a situation (social/subjective).
Interferir
B1This verb is used when an external factor influences, hinders, or disrupts a process or course of action. It is often used in neutral, formal, technical, or abstract contexts. It implies that the action changes the result or prevents something from working correctly.
O mau tempo vai interferir nos voos de hoje.
(The bad weather will interfere with today's flights.)
Não deixe o estresse interferir na sua saúde.
(Do not let stress interfere with your health.)
O uso de antibióticos pode interferir nos exames de sangue.
(The use of antibiotics can interfere with blood tests.)
Ele prometeu não interferir na decisão do juiz.
(He promised not to interfere with the judge's decision.)
O barulho da rua começou a interferir na minha concentração.
(The street noise started to interfere with my concentration.)
Intrometer-se
B2This is a reflexive verb that corresponds to "meddling," "butting in," or "prying." It implies crossing a social boundary by involving oneself in business or conversations where one does not belong or was not invited. It usually carries a negative connotation of rudeness.
Pare de se intrometer na vida dos seus vizinhos.
(Stop meddling in your neighbors' lives.)
Desculpe me intrometer, mas a porta está aberta.
(Sorry to intrude, but the door is open.)
Ela sempre tenta se intrometer nas nossas discussões.
(She always tries to butt into our arguments.)
Ninguém gosta de pessoas que costumam se intrometer onde não são chamadas.
(Nobody likes people who tend to meddle where they are not called.)
Eu não queria me intrometer, mas preciso dizer algo.
(I didn't want to interfere, but I need to say something.)
Summary
To choose the right word, consider the context: if something acts as an obstacle or alters a functional outcome (like a signal, a decision, or health), use interferir. If a person is being nosey or entering a private matter without an invitation, use intrometer-se.