Truth = verdade, true = verdadeiro. This expression in Portuguese differs from English. We say "é verdade". "é verdadeiro" is used, for instance, for original brands.
That always bothered me a bit, isn't it technically incorrect? Shouldn't it either be "é a verdade" or "é verdadeiro"?
I understand that "é verdade" is idiomatic, my question is more if it can be generalized to other nouns. Can I say for instance "é tristeza" or "é vergonha"?