H-stretcher

Definition: a reinforcing brace on the underside of furniture, consisting of three pieces: two to connect the front and back legs, and one crossbar stretching horizontally between them, to form the shape of the letter 'H'; dating from the Renaissance, it is found both in 'country furniture', such as Windsor chairs, but also in finer styles, such as Hepplewhite

Example: H-stretchers help to support weight-bearing pieces, like sofas and tables.