ridgepole

Noun

ridge=pole

WORDNET DICTIONARY

ridgepole(n = noun.artifact) ridge, rooftree - a beam laid along the edge where two sloping sides of a roof meet at the top; provides an attachment for the upper ends of rafters; Array

is a kind of beam

is a part of gable roof, saddle roof, saddleback, saddleback roof

ridgepole, n.

The timber forming the ridge of a roof, into which the rafters are secured. [1913 Webster]

For further exploring for "ridgepole" in Webster Dictionary Online