French language scholar, lexicographer, and philosopher whose monumental Dictionnaire de la langue française, 4 vol. (1863–73; “Dictionary of the French Language”), is one of the outstanding lexicographic accomplishments of all time. A close friend of the philosopher Auguste Comte (Comte, Auguste), Littré did much to publicize Comte's ideas.

Educated in medicine as well as English, German, Greek, Latin, and Sanskrit and Sanskrit philology, Littré was an ardent democrat who took part in the insurrection against King Charles X in 1830. In the decade that followed, he began preparation of a 10-volume translation of the writings of Hippocrates, completed in 1862. About the time the first volume appeared (1839), he became acquainted with the writings of Comte and was soon a fervent disciple, publishing many works on Positivism. After Comte lost his teaching position at the École Polytechnique, Paris (1842), Littré became one of his principal financial supporters. After 1852 he diverged from Comte's increasingly mystical views but waited until after Comte's death to publish his points of disagreement both in Paroles de philosophie positive (1859; “Words of Positivist Philosophy”) and in another work (1863), in which he traced the origin of Comte's ideas and analyzed his philosophical system and its effects.

When finally completed, Littré's dictionary, begun in 1844, proved to be of incomparable value for its precise definitions and historical grasp of the growth of the French language. The dictionary gives an authoritative interpretation of the use of each word, based on the various meanings the word had held in the past. After some controversy because of his materialist views, he was elected to the Académie Française (1871) and in 1875 was elected a senator for life.