The term 'not a thing' can be expressed in four different ways, each with a different number of letters. The first is 'NONE', which has four letters. This word is derived from the Old English word 'NAN', meaning 'not any'. The second is 'ZIP', which has three letters. This word is derived from the Yiddish word 'zippen', meaning 'NOTHING'. The third is 'NIL', which also has three letters. This word is derived from the Latin word 'NIL', meaning 'NOTHING'. The fourth is 'NADA', which has four letters. This word is derived from the Spanish word 'NADA', meaning 'NOTHING'. All four words express the same concept: that something does not exist.