Hammer-beam \Ham"mer-beam`\ (-b[=e]m`), n. (Gothic Arch.)
A member of one description of roof truss, called hammer-beam
truss, which is so framed as not to have a tiebeam at the top
of the wall. Each principal has two hammer-beams, which
occupy the situation, and to some extent serve the purpose,
of a tiebeam.
[1913 Webster]