sandhi

Sandhi is a term in linguistics describing the set of phonological changes that occur at word or morpheme boundaries. The word itself comes from Sanskrit, where sandhi means joining or binding. In practice, sandhi effects alter sounds to ease pronunciation and ensure smooth transitions between words, morphemes, or syllables. The phenomenon is particularly prominent in the languages of the Indian subcontinent, including Sanskrit, Pali, Prakrit, and their descendants such as Hindi, Marathi, Bengali, Tamil, and Kannada, though similar processes occur in many languages worldwide.

Sandhi is commonly categorized by location and by the type of sound change. External sandhi occurs at word boundaries; internal sandhi occurs within a word or compound. The rules can be highly systematic in some languages and more flexible in others, and they influence both spoken form and, in many cases, written orthography.

Common types and mechanisms include vowel sandhi, where adjacent vowels influence each other; consonant sandhi, where consonants at a boundary assimilate or alter; visarga sandhi, involving changes to the visarga symbol or its equivalents; and anusvara sandhi, involving nasalization sounds. These processes often involve assimilation to neighboring sounds, elision (loss of a sound), or epenthesis (insertion of a sound to break up a cluster). In many traditions, sandhi also interacts with prosody, morphology, and syntax, shaping how phrases are pronounced and how words connect in fluent speech.

In classical Sanskrit grammar, sandhi rules are highly formalized in Panini’s system; modern languages retain and adapt these processes to varying degrees, influencing pronunciation and spelling.