tri-tone en · ADJ
Etymology
From tri- + tone.
Meanings
-
(alt-of, alternative, not-comparable) Alternative form of tritone.
alt of tritone
A tri-tone chime whistle, operated from the cab by a flexible cable passing down the right hand handrail, is mounted on the top of the smokebox immediately behind the chimney.
1951 June, “British Railways Standard Class "5" 4-6-0 Locomotives”, in Railway Magazine, page 399: