
1) Double dagger
Found on
https://www.crosswordclues.com/clue/diesis

In classical music from Western culture, a diesis (s {respell|DY|ə-sis}; `difference`; Greek: δίεσις `leak` or `escape`) is either an accidental (see sharp), or a very small musical interval, usually defined as the difference between an octave (in the ratio 2:1) and three justly tuned major thirds (tuned in the ratio 5:4), equal to 12...
Found on
http://en.wikipedia.org/wiki/Diesis

double dagger sign
Found on
http://phrontistery.info/d.html

• (n.) A small interval, less than any in actual practice, but used in the mathematical calculation of intervals. • (n.) The mark /; -- called also double dagger.
Found on
http://thinkexist.com/dictionary/meaning/diesis/

Di'e·sis noun ; plural Dieses . [ New Latin , from Greek ..., from ... to let go through, dissolve; dia` through + ... to let go, send.] 1. (Mus.) A small interval, less than any in actual practice, but used in the mathematical calculation of intervals.
Found on
http://www.encyclo.co.uk/webster/D/62

In music a diesis is a small interval, less than any in actual practice, but used in the mathematical calculation of intervals.
Found on
http://www.probertencyclopaedia.com/browse/VD.HTM
No exact match found.