n. & v.
n. 1 a long sturdy piece of squared timber or metal spanning an opening or room, usu. to support the structure above. 2 a a ray or shaft of light. b a directional flow of particles or radiation. 3 a bright look or smile. 4 a a series of radio or radar signals as a guide to a ship or aircraft. b the course indicated by this (off beam). 5 the crossbar of a balance. 6 a a ship's breadth at its widest point. b the width of a person's hips (esp. broad in the beam). 7 (in pl.) the horizontal cross-timbers of a ship supporting the deck and joining the sides. 8 the side of a ship (land on the port beam). 9 the chief timber of a plough. 10 the cylinder in a loom on which the warp or cloth is wound. 11 the main stem of a stag's antlers. 12 the lever in an engine connecting the piston-rod and crank. 13 the shank of an anchor.
v. 1 tr. emit or direct (light, radio waves, etc.). 2 intr. a shine. b look or smile radiantly. beam-compass (or -compasses) compasses with a beam connecting sliding sockets, used for large circles. a beam in one's eye a fault that is greater in oneself than in the person one is finding fault with (see Matt. 7:3). off beam colloq. mistaken. on the beam colloq. on the right track. on the beam-ends (of a ship) on its side; almost capsizing. on one's beam-ends near the end of one's resources.
[ OE beam tree f. WG ]