quinticlave
/ˈkwɪntɪˌkleɪv/Music. Now chiefly historical
noun
A keyed brasswind instrument of the early 19th cent., a type of upright alto ophicleide.
Origin
1970s. From quinti- + classical Latin clāvis key, apparently after French †quinte à clef (undated), probably so called with reference to its pitch.