The term PREFIX WITH -CERATOPS can be solved by the THREE-letter word TRI. The prefix 'TRI-' is derived from the Greek language and means 'THREE'. It is commonly used in scientific terms to refer to something that has THREE parts or components. In this case, the prefix is being used with the word 'ceratops', which is a type of dinosaur that had THREE horns on its head. Therefore, the answer to the crossword puzzle is TRI, which is a prefix meaning 'THREE' when used with the word 'ceratops'.