A crosspiece is a bar, beam, or strip that lies across something else, connecting two sides or adding support. Picture a ladder: those horizontal steps you climb are crosspieces connecting the two long side rails. The horizontal bar on a capital letter “T” or “H” is a crosspiece. On a wooden fence, the boards that run sideways between the vertical posts are crosspieces.

Crosspieces serve important purposes in construction and design. They make structures stronger by distributing weight and preventing the sides from spreading apart. A chair might have crosspieces underneath the seat to keep the legs from wobbling. A kite has crosspieces that stretch the fabric into shape and help it catch the wind.

You'll see crosspieces in bridges, bed frames, picture frames, and countless other structures where two parallel parts need to be held together or braced. Any time you see something lying across another part, adding strength or connection, you're probably looking at a crosspiece.