"Fifteenth" is a word in ENGLISH

One of fifteen equal parts or divisions; the quotient of
a unit divided by fifteen.

A stop in an organ tuned two octaves above the diaposon.

A species of tax upon personal property formerly laid on
towns, boroughs, etc., in England, being one fifteenth part of what the
personal property in each town, etc., had been valued at.

An interval consisting of two octaves.

Next in order after the fourteenth; -- the ordinal of
fifteen.

Consisting of one of fifteen equal parts or divisions of
a thing.