Certain adjectives describe themselves and others do not. For example, ‘short’ describes itself, and so does ‘polysyllabic’. But ‘long’ does not describe itself, ‘monosyllabic’ does not, and nor does ‘green’. The word ‘heterological’ means ‘not describing itself’. The German mathematician K. Grelling pointed out what is known as Grelling’s paradox that results from considering whether ‘heterological’ describes itself or not. The paradox has some similarities with Russell’s paradox.