The Neogrammarians (also Young Grammarians, German Junggrammatiker) were a German school of linguists, originally at the University of Leipzig, in the late 19th century who proposed the Neogrammarian hypothesis of the regularity of sound change. According to this hypothesis, a diachronic sound change affects simultaneously all words in which its environment is met, without exception. Verner's law is a famous example of the Neogrammarian hypothesis, as it resolved an apparent exception to Grimm's law. The Neogrammarian hypothesis was the first hypothesis of sound change to attempt to follow the principle of falsifiability according to scientific method. Today this hypothesis is considered more of a guiding principle than an exceptionless fact, as numerous examples of lexical diffusion (where a sound change affects only a few words at first and then gradually spreads to other words) have been attested.
Other contributions of the Neogrammarians to general linguistics were:
Leading Neogrammarian linguists included:
Despite their strong influence in their time, the methods and goals of the Neogrammarians have been criticized from various points of view, but mainly for: reducing the object of investigation to the idiolect; restricting themselves to the description of surface phenomena (sound level); overvaluation of historical languages and neglect of contemporary ones.