In the Middle Ages, Old Occitan (formerly "Old Provençal"), the language of the troubadours, was a literary and cultural language, the influence of which extended far beyond the frontiers of Southern France.

The only comprehensive portrayal of the Old Occitan vocabulary to have appeared up to now is the "Lexique roman" by François Raynouard (6 vols., 1836–1845). It was supplemented by Emil Levy’s "Provenzalisches Supplementwörterbuch" (8 vols., 1894–1924). An updated dictionary, taking account of progress in research over the last 100 years, has been the desideratum of literary scholars, linguists, and historians ever since.

Under the direction of Wolf-Dieter Stempel, the publication of a new dictionary of Old Occitan, the "Dictionnaire de l'occitan médiéval (DOM)", began in 1996. This appeared in print until 2013, directed from 2012 on by Maria Selig. Since then it has been available as an alphabetically complete digital dictionary, the "DOM en ligne". This comprises the newly written articles of the DOM together with the articles from the dictionaries of Raynouard and Levy for those parts of the alphabet not yet covered by the new work and is enriched by entries for words absent till now from Old Occitan lexicography.

Its content is available for free at https://dom-en-ligne.de/dom.php