Incandescent means glowing brightly because of intense heat. When metal gets hot enough, it begins to glow, first red, then orange, then white. That glow is incandescence. The old-style light bulbs your grandparents grew up with were called incandescent bulbs because they worked by heating a thin wire until it glowed brightly enough to light a room.

The sun is incandescent: its enormous heat makes it shine. Lava flowing from a volcano glows incandescent orange and red. A blacksmith heating metal in a forge watches it become incandescent before hammering it into shape.

People also use incandescent to describe extreme emotion or talent that seems to shine from within. An incandescent performance by an actor means they glowed with such intensity and brilliance that you couldn't look away. An incandescent rage burns white-hot. When someone gives an incandescent speech, their passion and energy light up the room, like they're radiating light from pure intensity.