A fire is a blaze. Fire, when it's going strong and burning bright, is blazing. The greater the blaze, the harder a fire is to put out. You can also use this word for other types of brightness or shining.
In addition to normal weapons, Blazes can be hurt by snowballs, taking 3 (1 1/2 hearts) per hit. If they have found a way into the Overworld, they are also damaged by water and even rain: Water does roughly 1 damage every second. Like all Nether mobs, they are not damaged by fire or lava.