Definition of Lachmann's law in English:

Lachmann's law

Pronunciation /ˈlaxmənz ˌlɔː/

noun

  • The rule that, in Latin, a short root vowel in the present tense stem of a verb typically corresponds to a long vowel in the past participle if the present tense stem ends in a voiced plosive.

    The processes which gave rise to this pattern, the date of their occurrence, and the nature of their interaction with other phonological or morphological processes are all disputed.

Origin

Late 19th century; earliest use found in Classical Review. From the genitive of the name of Karl Lachmann, German philologist + law.