Conceptual dictionary

Onelook.com and Diccionario Ideológico de la Lengua Española (for Spanish)[1] are specific online and print examples.

This is sometimes called a reverse dictionary because it organized by concepts, phrases, or the definitions rather than headwords.

(For example, in a thesaurus one could look up "doctor" and be presented with such words as healer, physician, surgeon, M.D., medical man, medicine man, academic, professor, scholar, sage, master, expert.)

Such dictionaries have become more practical with the advent of computerized information-storage and retrieval systems (i.e. computer databases).

[1] This allows the user to find words based on a small set of general concepts.