fifteenth

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The ordinal number matching the number 15 in a series.
• noun One of 15 equal parts.

from The Century Dictionary.

• Next after the fourteenth: an ordinal numeral.
• noun The quotient of unity divided by fifteen; one of fifteen equal parts of anything: as, eleven fifteenths of an acre.
• noun In music, the interval or the concord of a double octave.
• noun In organ-building, a stop whose pipes are tuned two octaves above the keys struck.
• noun In early English law, a fifteenth part of the rents of the year, or of movables, or both, granted or levied by way of tax. When a fifteenth was the rate for the counties at large, that for towns and demesnes was usually a tenth.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Next in order after the fourteenth; -- the ordinal of fifteen.
• adjective Consisting of one of fifteen equal parts or divisions of a thing.
• noun One of fifteen equal parts or divisions; the quotient of a unit divided by fifteen.
• noun 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.
• noun A stop in an organ tuned two octaves above the diaposon.
• noun An interval consisting of two octaves.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective The ordinal form of the number fifteen.
• noun The person or thing in the fifteenth position.
• noun One of fifteen equal parts of a whole.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun position 15 in a countable series of things
• adjective coming next after the fourteenth and just before the sixteenth in position