The term 1st, 2nd, 3rd... NTH (3 letters) is a way of expressing ordinal numbers. Ordinal numbers are used to indicate position or rank in a sequence, such as first, second, third, and so on. NTH is the abbreviation for the word 'NTH, ' which is used to refer to any ordinal number beyond the tenth. For example, if someone were to say 'the 11th place finisher, ' they would be referring to the person who finished in the 11th position.