A horizontal or transverse beam, especially a structural beam resting on two supports.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "crossbeam" in a sentence
"Dangling by a wire from a crossbeam was a large white cardboard sign."
"Not that the teenage idiot I was who is, by the way, still swinging freely from a crossbeam and turning a lovely shade of blue would have believed that dopey, feel-good phrase anyway."
"Facing Tristan again, she found him sitting casually on the edge of the footbridge railing, one foot propped on a crossbeam, as if waiting on someone to hand him a beer."