José Roberto is very right on what he told you about how he deals with questions that he or any teacher is unaware of.

As for myself, I have learned overtime that it is best to say I don't know than to give out a meaning that's inaccurate.

You mentioned ACEROLA. Let me tell you that even in the USA when something new is brought over and it becomes popular it can keep its original name with a local accent, such as AÇAÍ.

Açaí is becoming more and more popular in the US because of its weight loss promise.

Now even of popular FM stations one can listen to açaí ads. The other day in one of those ads a lady was teaching this guy how to pronounce it by saying /ah-say/

Students should be encouraged to look up for meanings by themselves even while in class they can always check their dictionaries.