Final answer:
The second syntactic indicator to determine whether a word is a noun or not is derivational suffixes. Derivational suffixes are added to the base form of a word to create a new word with a different grammatical category or meaning.
Step-by-step explanation:
The second syntactic indicator to determine whether a word is a noun or not is derivational suffixes. Derivational suffixes are added to the base form of a word to create a new word. These suffixes can change the grammatical category or meaning of the word. For example, in the word 'happiness,' the suffix '-ness' changes the adjective 'happy' into a noun.