Wiktionary
a. 1 Lacking in power, especially electrical power. 2 Not using or requiring power, especially artificial power. For example, an unpowered boat (a sailing boat), aircraft (a glider) etc.
WordNet
adj. not having or using power; "an autogiro is supported in flight by unpowered rotating wings" [ant: powered]
Usage examples of "unpowered".
The tungsten-cored penetrators of the discarding sabot ammunition penetrated his antiballistic, unpowered armor effortlessly at such point-blank range.
When during takeoff a helicopter pilot detects or senses that something is not going exactly as it should be going, he can raise the forward end of the rotor cone, which reduces or eliminates forward speed, and he can thereafter make a powered or unpowered descent an autorotation to the ground immediately under him.
As a partial solution, men sometimes laid rows of static, unpowered black or white pieces along the rim of the playing field, to try constraining the action.
There was only enough unpowered body armor for a hundred and thirty people, but the small arms racks had been intended to provide every member of the company with side arms as well as pulse rifles, plasma rifles, or tribarrels.
The remainder of the eighteen armed personnel backing up the calliope crews and the cannoneers were either completely unarmored or wore only unpowered body armor.
He was facing perhaps the toughest moment of the flight, an unpowered deadstick landing.