beam [OE] As well as referring to a piece of wood, beam originally also meant ‘a tree’, a use that survives in the names of the hornbeam [L16th] and whitebeam [ME]. Sailors understood a beam to be one of the timbers stretching from side to side of a ship, supporting the deck and holding the vessel together. From there beam came to mean a ship’s greatest breadth [E17th]. This is why you can call someone broad in the beam [E20th], ‘wide in the hips’. A ship that is on its beam ends [L18th] is heeled over on its side, almost capsized, and so if a person is on their beam ends they are in a very bad situation.

The beam in your eye, the fault that is greater in yourself than in the person you are finding fault with, comes from the Bible. Jesus contrasts the large beam unseen in someone’s own eye with the mote (‘speck’) noticed in the eye of another. ‘Beam me up, Scotty’ will forever be associated with the American television series Star Trek, as the words with which Captain Kirk asked Lieutenant Commander Scott to ‘beam’ or transport him from a planet back to the starship USS Enterprise. The exact words, however, do not occur in any of the television scripts, although it was later used in the films. The beam of light or sunbeam [OE] is the same word, adopted from similar uses in Latin.