[Vocabulary] Help please

[Pepperoni Papaya]

What do you call 2 people sing a song or play music together? :-D

 

[Raymott]

What do you call 2 people sing a song or play music together? :-D

A duet.
3 is a trio
4 is a quartet
5 is a quintet
etc.

No, 1 isn't a singlet! It's a solo.

 

[emsr2d2]

I believe that a song sung by two people is a duet, the performance of such a song is also called a duet, two people singing together is "to duet", but that the name for the two people together is normally a duo.

Freddie Mercury and Monserrat Caballe duetted on "Barcelona".
Britney Spears and Cristina Aguilera have never done a duet.
The talented duo [of] Simon and Garfunkel wrote some very famous songs.

 

[Raymott]

I believe that a song sung by two people is a duet, the performance of such a song is also called a duet, two people singing together is "to duet", but that the name for the two people together is normally a duo.

Freddie Mercury and Monserrat Caballe duetted on "Barcelona".
Britney Spears and Cristina Aguilera have never done a duet.
The talented duo [of] Simon and Garfunkel wrote some very famous songs.

Yes, 'duo' is also used.
But "Duet" is also used as a verb for the act of performing a musical duet, or colloquially as a noun to refer to the performers of a duet."
Duet - Wikipedia, the free encyclopedia
So, both are possible.