The problems inherent in efforts to create large lexical databases by mapping machine-readable dictionaries onto each other are illustrated through an attempt to merge manually two short entries (whistle and whistler) from two monolingual English collegiate-style dictionaries. In view of the complexities revealed by this operation for the human mind, let alone the machine, we suggest that if lexical databases are to be created by automatic or semi-automatic means, it is essential to design the complete database first, following the demands of the language as identified by theoretical linguistic research, and only then to attempt to map the contents of any machine-readable dictionary into this ‘ideal’ database. We exemplify part of the suggested template lexical entry for verbs of sound, including whistle. 1