Wiktionary
a. In the horizontal direction away from the launch site of a rocket in the direction of its travel. adv. In the horizontal direction away from the launch site of a rocket in the direction of its travel.
Wikipedia
Downrange is the horizontal distance traveled by a spacecraft, or the spacecraft's horizontal distance from the launch site. More often, it is used as an adverb or adjective specifying the direction of that travel being measured in a horizontal direction.
In military slang, downrange is a term for being deployed overseas, usually in a war zone. It is also the name of a comic strip published in the newspaper Stars and Stripes.
Usage examples of "downrange".
He bumped the jeep to a point about ten feet downrange from the slabs, put the emergency brake on, and shut off the engine.
It pawed the ground and caracoled but stayed in one spot, some one hundred meters and more downrange, in what looked to be a shaft of sunlight.
Billy Lee pulled the trigger, and a burst of nine-millimeter slugs went downrange, and the black kid tumbled ass over teakettle into the weeds.
The heavy calliope's feed mechanism howled as the disintegrating link ammo belt blurred into the feed chute, and the penetrators shrieked downrange.
Gently squeeze the trigger until the firing mechanism goes off and a plasma bolt, projectile, or beam moves downrange at the target.
The metal sublimed from powergun bores as they channeled the enormous energy downrange and redepos-ited on whatever was closest when the vapor cooled.