  Preparing exact and comprehensive word meaning explanations is one of the key
steps in the process of monolingual dictionary writing. In standard
methodology, the explanations need an expert lexicographer who spends a
substantial amount of time checking the consistency between the descriptive
text and corpus evidence. In the following text, we present a new tool that
derives explanations automatically based on collective information from very
large corpora, particularly on word sketches. We also propose a quantitative
evaluation of the constructed explanations, concentrating on explanations of
nouns. The methodology is to a certain extent language independent; however,
the presented verification is limited to Czech and English. We show that the
presented approach allows to create explanations that contain data useful for
understanding the word meaning in approximately 90% of cases. However, in many
cases, the result requires post-editing to remove redundant information.
