Question

what is meant by non terminating decimal

Answer 1

Definition of nonterminating

not terminating or ending; especially : being a decimal for which there is no place to the right of the decimal point such that all places farther to the right contain the entry 0. 
¹/₃ gives the nonterminating decimal.

Answer 2

being a decimal for which there is no place to right to the decimal point such that all places farther to right contain the entry 0.1/3 gives the nonterminating decimal .33333..."