Research studies have demonstrated that children tend to define nouns by describing first their function and later the object to which they refer. In a study devised to trace the development of noun definition in the language of grade school children and adults, 20 subjects from each of four grade levels (kindergarten and grades two, four, and six) and 20 adults were asked to define 15 common nouns under two separate conditions: with the objects present and without the objects present. Definitions were classified as concrete, functional, or a combination of the two and were analyzed by grade level of subjects, condition, and category. The study revealed that both children and adults consider function to be the main determinant of noun meaning, that concrete aspects are introduced at about the fourth grade and are used to distinguish between and within concepts, and that the use of analogies is a strategy to make a definition more explicit and is not a part of the definition itself. The study supported a cognitive-linguistic explanation of noun definition development in that it showed that a shift from functional to combinatorial definitions occurs with increasing age. (MAI)