Why is Plasma TV called Plasma TV?

It's because of the way they work. They apply electricity to neon and xenon to produce UV light to light up a phosphor. When neon and xenon get a spark, they go from a gas to plasma, a fourth state of matter (liquid, gas, solid and plasma.) A kid might say it's called a plasma TV because it is so thin, which is an invalid and incorrect answer because he wasn't considering that LED TVs are even thinner.