Nharmonics 

1 - The act of being kick ass.
2 - The most rocked out A capella group at NYU.
3 - The envy of all others.
4 - One note with two different names.

1 - That shit is so NHARMONICS.
2 - Did you hear the NHARMONICS last night? They dropped a tight ass beat yo.
3 - I wish I was in NHARMONICS. Don't you?

Nharmonics by dirk January 25, 2005

inharmonicity 

The degree to which the frequencies of overtones (known as partials, partial tones, or harmonics) depart from whole multiples of the fundamental frequency.

in stringed instruments such as the piano, violin, and guitar, the overtones are close to—or in some cases, quite exactly—whole number multiples of the fundamental frequency. Any departure from this ideal harmonic series is known as inharmonicity. The less elastic the strings are (that is, the shorter, thicker, and stiffer they are), the more inharmonicity they exhibit.

inharmonicity by noduesp July 20, 2011

illharmonic 

music that mixes classical elements and hip hop elements.

LL Cool J's song "The Crossroads" was an early illharmonic track.

illharmonic by cool walt August 3, 2010