Airy:  Spaciousness, often a pleasant mostly treble-based reverb sound.  Extended frequency response that runs up through the top end of the bandwidth.

Brittle:  Peaking in high-frequencies, weak fundamentals with slightly distorted or harsh highs.

Crisp:  Good high-frequency response with good transient quality

Crispy:  Constant, but perhaps random high frequency sounds not unlike frying foods.

Delicate: Extended high frequency range without being harsh.  Emphasis on high frequencies extending to 20 KHz, but without the peaking. 

Edgy:  High frequency emphasis from about 3.5 to 6 KHz with harmonic content overly strong in comparison to fundamentals.  Can deal with high frequency distortion and rasp.

Piercing:  Hard on the ears, screechy and sharp.  Narrow peaks occurring between 3 and 10 KHz.

Raspy:  Harsh sounds in the 6 KHz range that sounds like a scratchy voice.

Sibilant:  S and Sh sounds are overly emphasized. 

Sizzly:  Similar to crisp, like the sound of the decay on a riveted cymbal.

Steely or Shiny:  Lots of top end from 3-6 KHz with peaky highs (as opposed to flat but boosted top end)

Sweet:  Flat high-frequency response without distortion and extended the full bandwidth.