
1) Adjective for XI 2) Being one of 11 equal parts 3) Describing a crucial hour 4) Latest possible hour 5) Like President James K Polk 6) Near-final hour 7) Next after the tenth 8) Ordinal 9) Steel anniversary 10) Veterans Day month or day 
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https://www.crosswordclues.com/clue/eleventh

 In music or music theory an eleventh play is the note eleven scale degrees from the root of a chord and also the interval between the root and the eleventh. The interval can be also described as a compound fourth, spanning an octave plus a fourth. Since there are only seven degrees in a diatonic scale the eleventh degree is the same as the subdomi...
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http://en.wikipedia.org/wiki/Eleventh

• (a.) Next after the tenth; as, the eleventh chapter. • (a.) Constituting one of eleven parts into which a thing is divided; as, the eleventh part of a thing. • (n.) The quotient of a unit divided by eleven; one of eleven equal parts. • (n.) The interval consisting of ten conjunct degrees; the interval made up of an octave and ...
Found on 
http://thinkexist.com/dictionary/meaning/eleventh/
 E·lev'enth  adjective
E·lev'enth  adjective [ Confer Anglo-Saxon 
 endlyfta . See 
 Eleven .] 
 1.  Next after the tenth; as, the 
 eleventh chapter.  
 2.  Constituting one of eleven parts into which a thing is divided; as, the 
 eleventh part of a thing.  
 3.  (Mus.) Of or pert...
Found on 
http://www.encyclo.co.uk/webster/E/21
 E·lev'enth  noun   1.
E·lev'enth  noun   1.  The quotient of a unit divided by eleven; one of eleven equal parts.  
 2.  (Mus.) The interval consisting of ten conjunct degrees; the interval made up of an octave and a fourth. 
Found on 
http://www.encyclo.co.uk/webster/E/21

In music, an eleventh is the interval consisting of ten conjunct degrees, that is the interval made up of an octave and a fourth.
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http://www.probertencyclopaedia.com/browse/VE.HTM

[
adj] - coming next after the tenth and just before the twelfth in position 2. [n] - position 11 in a countable series of things
Found on 
http://www.webdictionary.co.uk/definition.php?query=eleventh
 11th adjective
11th adjective coming next after the tenth and just before the twelfth in position
Found on 
https://www.encyclo.co.uk/local/20974

next after the tenth; being the ordinal number for 11. · being one of 11 equal parts.
Found on 
https://www.infoplease.com/dictionary/eleventh
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