Sinto-me meio coiso

15:51 Oct 27, 2020 

To be sure, off, odd, weird, or whatever, what is the phrase after how she/he feels "coiso"? Is there any reference to pain, dizziness, fatigue... Is the person apathetic or exited? With such information, any of the answers given by Nick, Tereza, Barbara, Fernando or Muriel can be adequately chosen.

12:42 Oct 27, 2020 

Feeling a bit "off" - probably a contraction of feeling a bit "off colour" (in grandadspeak) that is :-)

12:09 Oct 27, 2020 

I believe we live on the same side of the pond, as I am in Canada and you are in the USA. ‘Odd’ and ‘off’ are commonly used here, and so are all the other expressions suggested. It’s just a matter of choice. There are, of course, regional differences as both countries are so big, but I wouldn’t say that ‘odd’ and ‘off’ are only used in European English.

11:14 Oct 27, 2020 

We would not say "odd" or "off" on this side of the Pond. Maybe something more international but still idiomatic.

10:57 Oct 27, 2020 

It is an idiomatic expression, very informal and specific to certain areas. It means that he was feeling a bit weird, a bit "blah" but couldn't really pin point the exact word to say. All of the recommendations so far are correct but just keep in mind the style. If you need to keep it informal, I would say weird/off.

19:59 Oct 26, 2020 

Excellent explanation, Egon! ‘Coisa’ is a very versatile word in Portuguese.

19:41 Oct 26, 2020 

"Estou meio coisado/coiso" is a way of saying you're not quite well but you're not sure what's wrong. You can also say it when you forget the exact word you wanted to say. Example: "Gente, esse faca não tá coisando". Here the person forgot that a knife "corta" (cuts).
It is a really really informal (I would say it is almost "wrong") way of communicating something.