The Collaborative International Dictionary of English v.0.48:
Ridgepole \Ridge"pole`\, n. (Arch.) The timber forming the ridge of a roof, into which the rafters are secured. [1913 Webster]WordNet (r) 3.0 (2006):
ridgepole n 1: 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 [syn: ridge, ridgepole, rooftree]