[Doomonyou]

I'm talking about scopes and goggles that work off of heat, as opposed to light. The variations in temperature of a body and equipment make it stand out against the ground and sand in the air.

That would be in-fir-red.

[MP5SD]

That would be thermal imagery

[Robert A Cook PE]

"That would be in-fir-red.

Nah.

Infrared is what you use to see heat sources through smoke and haze, or at night.

In-fir-red is what Santa Claus wears as camoflauge in a pine forest.

... and In-fire-d is what a Smokey the Bear wears in a pine forest.