Definition of "three-sided" [three•-sid•ed]

• Having three sides, especially three plane sides. (adjective)

Gnu Collaboartive International Dictionary of English: licensed under The Code Project Open License (CPOL)

• "Burke was there for the birth of the so-called triad, the three-sided nuclear force—missiles, manned bombers, and submarines—the U.S. was embarked upon building."
• "For the uninitiated, that's handball played on a three-sided court, modelled on the space between two buttresses of Eton chapel."
• "It was a telescope, protected by a tiny three-sided wooden gazebo."