During the time I've spend in Portugal, I seem to have heard people use "descansar" for situations that I would use 'relax' in English. They didn't rest, rather they stopped doing whatever was tiring them and did something else that was not demanding of energy or thought. 'Rest' would mean that they lay down or sat still.
Well, you have a point, it's just that I'm a language purist, a feature not shared by almost none of my countrymen :-) In everyday usage, you would be right, people do use it to mean both. In textbook form, it's the same as in English. It's not coincidence that if you look "relaxar" up in the dictionary, other meanings given are "to loosen, to weaken, to fail to perform your duties, or to become corrupted or immoral". That sounds more like relaxing than resting to me. Of course, what it really gives away is the influence Catholicism had in the shaping of society and thus, language.
Descansar is to recover from tiredness. (Tired = Cansado - Recovered from tiredness = Descansado)
Relaxar is to relieve the stress or tension (most common meaning). May be used to simply sit back and relax. Or relax the muscles, or as told before, to stop your efforts and let things undone, or badly done.
Um homem relaxado mostly means that he doesn't care enough for his responsibilities.
Haha! Yeah. But keep in mind, that last one is extremely old-fashioned, decades-old, at least. Maybe it survives in the seminar, who knows. And the one pertaining to the failure of your duties is not that much used, also a bit old-fashioned, I would say. The important thing is, you got the primary meaning.
This is one of the funnier discussions I've seen! Smiles are good. Also, although using relaxed to mean becoming corrupted or immoral is certainly not common today, English speakers would know exactly what you meant if you said "He has relaxed principles/morals/scruples/etc.." I only point that out because it's kind of a creative, poetic use of "relaxed" by today's standards. In short, this usage indeed can survive outside the seminary. :)
di (Português carioca) --> dji (English) especially when it's un accented. Likewise ti --> tchi. Short, unaccented e's often become i. When you play the audio word-for-word (turtle pace), words are pronounced more like they're spelled, but in conversation things get run together; e.g.: o menino --> u meñinu; este --> estchi. In Bahía they live in the Nor·des·tyi, but in in Rio they call it nordjeschi.