A Mixer/Engineer descriptor Terms

[Alex!]

Flat: Can either refer to something that a bit off key on the lower end or something sound lacking
Sharp: Can either refer to something that is a bit off key on the higher end or something is painful in the high end
Muddy: Can refer to something when there is no clarity in sound and sounds like walking in mud which can come from reverb or excess low end
Dull: Needs more high end
Too Sweet: too much high end
Dense: too much sound or too much low end
Messy: fix arrangement in order to bring out character 
Mono: No pan
Harmonics: tones that ring out above the main pitch that may be a nuisance in lower registers 
Digital distortion: can happen when sound is TOO LOUD

If you have anymore to add, add it to this forum 
In collaboration, communication is key so it would be nice to see more clarity

[trapbeat349]

This may be helpful in the future

Thanks

[fox]

digital distortion divergent dream

[Lopyt]

clipping happens when the waveform exceeds the digital volume limit,and the waveform is modified by distortion, which is often not favourable

Gain is volume basically

Dynamic tange is the range of volume from high volume to low volume, some instruments like a metal guitar, have low dynamic ranges, where a drum kit has a high dynamic range.

[Alex!]

Automation: Basically Markers on OS
Stereo: when things are panned
Velocity: note volume