Real Dictionary

beam
A beam is a line of energy, radiation, or particles sent in a particular direction.
verb: If you say that someone is beaming, you mean that they have a big smile on their face because they are happy, pleased, or proud about something.

beam in American English
the squared-off trunk of a tree
to give out (shafts of light); radiate in a beam or beams
to shine brightly; be radiant
noun: any of various relatively long pieces of metal, wood, stone, etc., manufactured or shaped esp. for use as rigid members or parts of structures or machines

beam in British English
noun: a long thick straight-sided piece of wood, metal, concrete, etc, esp one used as a horizontal structural member

beam in Mechanical Engineering
noun: A beam is a horizontal part of a structure used to carry a load.