decima
A tenth, particularly — A tithe or tax of one-tenth (now usually in historical Italian contexts).
He brandished his title as apostolic commissioner in court, and as supervisor of the papal decima in Tuscany.
A tenth, particularly — A tenth: a note nine degrees of the scale above or below a given note (and thus ten degrees separate counting inclusively) or the interval between such notes.
obsolete
A tenth, particularly — An organ stop a tenth above the normal 8-foot pitch.
Where it comes from
Borrowed from Latin decima (“a tenth”), now particularly via Italian decima. Doublet of decim, decime, and dime.
Adapted from the Wiktionary entry decima (CC BY-SA 4.0).