On reading the title of this post, readers would have immediately been able to provide the answer and may have wondered why I was even asking it.
But as I was writing my impressions of Lucia di Lammermoor and the sextet that is sung there, it struck me that while I knew the names for groups of singers of almost all sizes from two to ten (duet (two), quartet (four), quintet (five), sextet (six), septet (seven), octet (eight), nonet (nine), and dectet (ten)), I did not know the term for three singers. So I looked it up and (duh!) it is ‘trio’, a common word that I was very familiar with. After all, the Kingston Trio was a very popular group in my youth.
So why could I not recall this very obvious word? The answer may lie in the fact that the human brain retrieves information by following links from whatever starting point triggered the memory process. Since my curiosity had been piqued by the word ‘sextet’ and branched out from there, it probably began searching for a word that ended with ‘et’ in order to fit the pattern and it appears that there is none.
It is interesting how the brain makes associations, so that a piece of information that one cannot recall because it is being searched for in one context is easily recalled in another. If I had been thinking of other forms of music, such as folk or jazz, then the word ‘trio’ would have come to mind immediately since they are so commonly used in those genres.
I don’t know why no word ending with ‘et’ was coined for groups of three but then English is full of exceptions to patterns. Maybe there had been a word at some time (‘triet’?) that slowly disappeared from common use.