Musical term that can mean almost anything you want it to mean. Distortion, reverb, heavy bass, just about anything that isn't... uh... "cold". Basically synonymous with "good". Unless it's TOO "warm". Used mostly when talking about synthesizers, guitars, or recording.
Not to be confused with "fat" or "phat".
-"But listen to how WARM it sounds!"
-"Do you mean the mild distortion?"
-"Nah man, it's WARM!"
-"'Warm' is something you feel. It means nothing when talking about music. Water is warm, music is not warm. You're using a blanket term to cover up for your own lack of knowledge. Advertisers only use it because they're pandering to idiots like you."