Duet, Trio, Quartet, Quintet, Sextet, etc. Why is “trio” in here instead of tritet?

Question

Duet, Trio, Quartet, Quintet, Sextet, etc. Why is “trio” in here instead of tritet?

In: 154

Answer 1

If you are generally considering only vocal parts then you could also use the term terzet (the group), or terzetto (with regard to a vocal composition for 3).

With that said trio covers the gamut of groups of three people or things. Since singers may be playing musical instruments a trio would be more correct and thus trio gains favor.