From an unused root meaning to connect; a girder -- beam.
H3714. kaphis
כָּפִיס noun masculine apparently (si vera lectio) technical term for some beam in a house, perhaps rafter, or girder (Late Hebrew id., Levy, Jastrow, but according to HoffmZAW ii. 1881, 71 it is changed from oblong block of wood (O.T.) to a building-stone, or brick in Mishna); — only Habakkuk 2:11 for a stone out of the wall crieth out, ׳וְכ יַעֲנֶנָּה מֵעֵץ and a rafter out of the timber-work answereth it.