nut [OE] The Old English word nut is related to the Latin nux, also meaning ‘nut’, and to *nucleus. The informal meanings ‘crazy or eccentric person’ and ‘person who is excessively interested in a particular thing’, both date from the early 20th century. They probably come from the informal sense ‘a person’s head’. This latter sense is the one behind phrases such as do your nut, or get very cross, and is the root of nutty meaning ‘mad or crazy’. It is also the source of the verb ‘to nut’, or butt with the head, which is first found in the 1930s. See also fruit. A nutshell has been used since the late 16th century to symbolize compactness or shortness. Shakespeare’s Hamlet says, ‘I could be bounded in a nutshell, and count myself a king of infinite space, were it not that I have bad dreams.’ The idea is thought to have come from the supposed existence of a copy of Homer’s epic poem, the Iliad, which was small enough to fit into an actual nutshell, mentioned by the Roman scholar Pliny (ad 23–79) in his Natural History.