The term NOUN-MAKING SUFFIX refers to two common suffixes used to create nouns from other words. The first is 'NESS, ' which is a four-letter suffix that is added to adjectives to create nouns. For example, the adjective 'HAPPY' can be turned into the noun 'HAPPINESS' by adding 'NESS.' The second suffix is 'ence, ' which is also a four-letter suffix that is added to verbs to create nouns. For example, the verb 'DEFEND' can be turned into the noun 'DEFENSE' by adding 'ence.'