Definitions as theories of word meaning

Dictionary definitions are often used in education and in computerized databases for processing natural language, but their accuracy as models of word meaning has not been carefully evaluated. An experiment involving fourth graders and adults measured the efficacy of dictionary definitions in marking distinctions in sense and found them to be very poor for children, but fairly helpful for adults. A second experiment compared dictionary definitions to definitions written by college students who had sorted sets of sentence citations, and found both moderately effective in teaching word use. Good definitions were produced less often for high-frequency words than for low-frequency words, given equivalent numbers of citations, suggesting that sentences using high-frequency words are less informative overall. Also, the more citations available to the definition writer, the better the definition was in teaching word use, suggesting that information about word meaning is cumulative and describable.This research was partially supported by grants from the Spencer and Sloan Foundations to George A. Miller.