BEAM. Used in the OT to refer to beams used in constructing the upper floors and roofs of buildings (1Kgs.7.3) and to the beam of a weaver’s loom (Judg.16.14). Jesus uses the term in a figurative sense in Matt.7.3 and Luke.6.41 (niv “plank” in both cases) in contrast to a mote, in order to show how inconsistent it is to criticize minor faults in others when ours are so much greater.
The weaver’s beam in Judges 16:14 ASV, RSV is actually the weaving frame. The beam of Habakkuk 2:11 (כָּפִיס, H4096) is a splinter. The beam in Matthew 7:3 ASV; passim, δοκός, G1512, is the tiny speck that irritates.
International Standard Bible Encyclopedia (1915)
bem: The word is used to translate various Old Testament terms:
(2) Beam, in weaving, represents two words, ’eregh (Jud 16:14, the beam of a loom to which Samson’s hair was fastened; used in Job 7:6 of a weaver’s shuttle), and manor (1Sa 17:7; 2Sa 21:19; 1Ch 11:23; 20:5), of a spear-staff.
(3) In the New Testament Jesus uses the word dokos, "a rafter," in bidding the censorious person first cast the "beam" out of his own eye before attempting to remove the "mote" from another’s eye (Mt 7:3; Lu 6:41,42).
See Architecture; House.
Arch. C. Dickie