sesquialtera
/ˌsɛskwɪˈalt(ə)rə
/adjective Music
1Relating to or denoting a ratio of 3:2, as in an interval of a fifth.
1.1Denoting an organ stop typically consisting of two ranks of narrow-scaled open flue pipes.
Origin
Late Middle English: from Latin, feminine of sesquialter, from sesqui (see sesqui-) + alter 'second'.