A type of music so innocuous as to round the bend and be remarkably obnoxious. Always instrumental, and most often featuring a noodly overdriven guitar lead, though saxophones, usually soprano saxophones, are also common. Frequently heard as telephone on-hold music.
"Fuzak" is a portmanteau of "fusion", short for "jazz-rock fusion", used as synecdoche for "smooth jazz", a style of music known for its blandness, and "muzak", a genericized trademark referring to "elevator music".
If I have to listen to any more tech support fuzak, I'm going to turn into a gibbering idiot.