On some views of language, when one uses a term to describe or label an object, a contrast is always implied. However, there is an important difference between nouns and adjectives in their contrastive use: adjectives imply a contrast between members of a single noun category, whereas nouns do not imply a contrast between members of a single adjective category. For example, describing a car as new suggests a contrast with other cars. However, labelling it as a car does not as clearly imply a contrast with other new objects. There is no logical necessity for this distinction – it is not captured by the literal meanings of words. Yet it is a conceptual distinction implicit in the use of these terms. In two studies, we tested preschool children's appreciation for this conceptual distinction, using both familiar and unfamiliar words. In Study I, 4-year-olds (but not 3-year-olds) were able to disambiguate the meanings of simple nouns and adjectives by assuming that the adjectives, unlike the nouns, implied a contrast between category members. In Study II, children selected pictures to match totally novel adjectives and nouns (e.g. the fep one, the skub). Relying on part of speech alone, they interpreted these unfamiliar nouns and adjectives differently. Implications for children's use of referential language and word-learning strategies are discussed.