Fortunatov's law

Fortunatov's law is the observation, in the development of Sanskrit from Proto-Indo-European, that when *l is followed by a dental consonant, the dental becomes retroflex and the *l is deleted, eg. PIE *bʰelsos > Sanskrit bhā́ṣā (compare Lithuanian bal̃sas) and PIE *poltos > Sanskrit paṭa, Greek péltē. This law is not uniform.