Qualitative developments in the content and form of children's definitions.

This research examined qualitative developments in school-age children's (N = 96) expressible knowledge of a sample of 434 words selected to represent the contents of a large unabridged dictionary. Definitions were classified according to the quality of both semantic content and syntactic form. Analyses revealed developmental increases in the proportions of known words and in the relative proportions of definitions credited for high-quality content and/or form. Children generally were more successful in expressing precise semantic content than in using conventional syntactic form. The work characteristics of part of speech and morphological composition also affected definitional quality, with coordination of high-quality content and form achieved earlier for root and compound nouns than for inflected and derived nouns for verbs and adjectives of all morphological types. Both lexical organization and differential experience may support the earlier use of conventional definitional form for root and compound nouns than for other word types. The results provide a more complete picture of the development of definitional skills.