nerve [LME] In the Latin from which it was borrowed nervus had a wide range of meanings including nerve, sinew, penis, plant fibre, strength, vigour, and energy. It probably shares an Indo-European root with Greek neuron, source of neuron [L19th], which had much the same range of meaning. The sense ‘courage, boldness’ did not appear until the early 19th century and the sense ‘impudence’ is late 19th century.