Brighten - Add high frequencies.
More/less warmth - Add or attenuate low frequencies.
Subbass - The lowest bass ranges, often more felt in the body than heard due to the lack of harmonics. We assume these are values from 20 Hz to 60 Hz.
Bass/Low - Ranges from 60 Hz to 250 Hz.
Low mid - Ranges from 250 Hz to 500 Hz.
Mid - Middle ranges. We assume these are frequencies around 1 kHz, but they can often range from 500 Hz up to 2 kHz. So we start looking from 1 kHz.
High mid - Ranges from 2 kHz to 5 kHz.
High - Ranges from 6 kHz to 20 kHz.
Air - Similar to Subbass, this is almost the boundary of human audibility. Therefore, we assume that above 14 kHz up to 20 kHz we are dealing with "air" frequencies.
Muddy/Blurry - Lacking high frequencies, not very detailed. Perhaps too saturated with reverb.
Too sharp - Painful sound, especially at higher volumes. Most often too much mid or high frequencies.
Glassy/metallic - Too many high frequencies - usually everything above 10 kHz.
Flat dynamics - Usually little energy and detail in the rhythm section. Not very expressive drums, poorly compressed, lacking accent - primarily a bad volume balance. Perhaps a very quiet snare/kick drum.