Sources

• George L. Hart, A Rapid Sanskrit Method (Delhi: Motilalal Banarsidas, 1984)1

An excellent summary of sandhi rules in the form of look-up charts can be found at the University of British Columbia’s Sanskrit resource site.

Vowel Lengthening

Vowel	अ	आ	इ,ई	उ,ऊ	ऋ
Guṇa (गुण)	अ	आ	ए	ओ	अर्
Vṛddhi (वृद्धि)	आ	आ	ऐ	औ	आर्

Rules

1. Final –स् becomes : (visargaḥ / विसर्गः) at the end of an utterance.
2. Final –म् becomes ं (anusvāra / अनुस्वार) before an initial consonant.
3. When two similar vowels (short or long) come together, they are replaced by the similar long vowel. (Hart 1)2
   • न + अपि → नापि
   • हि+ इति → हीति
   • साधु + उक्तम् → साधूक्तम्
4. When –अ or –आ precede an initial dissimilar vowel, both are replaced by the guṇa of the dissimilar vowel. (Hart 2)
   • च + इह → चेह
   • च + उक्तम् → चोक्तम्
   • च + ऋषि → चार्षि
5. When final –अ or –आ precedes an initial diphthong, both are replaced by the vṛddhi of the diphthong’s second element. (Hart 3)
   • च + एति → चैति
   • सा + ओषधिः → सौषधिः
   • सेना + ऐश्वर्यम् → सेनैश्वर्यम्
   • इह + ओन्नत्यम् → इहौन्नत्यम्
6. When vowels, long or short, other that –अ or –आ precede a dissimilar vowel or diphthong, the initial vowel is replaced by its corresponding semivowel. (Hart 4)
   • यदि + अपि → यद्यपि
   • भवतु + एवम् → भवत्वेवम्
   • होतृ + ओषधिः → होत्रोषधिः
7. Before initial अ-, final ए– and ओ– are unchanged but the initial अ– is elided and replaced by an avagraha (अवग्रह) or ऽ which is not pronounced. (Hart 5)
   • वने + अपि → वनेऽपि
   • सो + अपि → सोऽपि
8. Before vowels or diphthongs other than –अ, ए and ओ are replaced by अ, and the hiatus remains. (Hart 6)
   • वाने + आगच्छ → वान आगच्च
   • प्रभो + एहि → प्रभ एहि
9. Before all vowels and diphthongs, ऐ becomes –आ, and the hiatus remains; औ becomes –ाव and the hiatus does not remain. (Hart 7)
   • कस्मै + अपि → कस्मा अपि
   • देवौ + अपि → देवावपि
10. Exception: ī, ū, and e as dual endings of nouns and verbs are unchanged before initial vowels. Also an exception is the final vowel of interjections. These vowels are called pragṛhya (प्रगृह्य).
    • हे + अश्व → हे अश्व (“O horse”)
    • फले + अपि → फले अपि (“Even the two fruit …”)
11. –अस् before all voiced consonants including ह– becomes ो. (Hart 8)3
    • देवः + गच्छति → देवो गच्छति
    • नृपः + विशति → वृपो विशति
12. –अस् before अ– becomes ो and the अ– becomes an avagraha, ऽ. (Hart 9)
    • देवः + अत्र → देवोऽत्र
13. –अस् before all vowels and diphthongs except अ– loses its final –स्. (Hart 10)
    • देवः + एव → देव एव
    • नृपः + आगच्छ → नृप आगच्छ
14. –आस् before all vowels, diphthongs and voiced consonants including ह– loses its final –स्. Before vowels the hiatus remains. (Hart 11)
    • देवाः + विशन्ति → देवा विशन्ति
    • देवाः + अपि → देवा अपि
    • नृपाः + हि → नृपा हि
15. –स् and र् become ः before क-, ख-, प-, फ-, श-, ष– and स-, and at the end of an utterance. (Hart 12)
    • देवः + कुत्र → देवः कुत्र
    • देवः + फलं → देवः फलं
    • नृपः + स्मरति → नृपः स्मरति
    • पुनर् + कुत्र → पुनः कुत्र
    • आगच्छेः + खलु → आगच्छेः खलु
16. –स् or –र् before च, छ, ट, ठ and त, थ are assimilated to the class of those letters (i.e., before च, स becomes palatal श, etc.) (Hart 13)
    • नृपः + चरति → नृपश्चरति
    • नृपः + तिष्ठति → नृपस्तिष्ठति
    • पुनर् + तिष्ठन्ति → पुनस्तिष्ठन्ति
17. After any vowel other than अ– and आ-, –स् becomes –र् before all vowels, diphthongs, and voiced consonants including –ह. (Hart 14)
    • पुत्रयोः + हि → पुत्रयोर्हि (पुत्रयोर् हि)
    • गच्छेः + अपि → गच्छेरपि
18. Final –र्, whether original or derived from –स् according to rule 17 (Hart 14), disappears before initial र-. If the vowel before the final –र् is not long, it is lengthened. (Hart 15)4
    • नृपतिः + रामते → नृपती रामते
    • पुत्रयोः + रथः → पुत्रयो रथः
    • पुनर + रामः → पुना रामः
19. Before ज– and श-, –न् become –ञ्. If श– is the initial letter of the next word, it is replaced by छ-. (Hart 16)
    • देवान् + जयति → देवाञ्जयति
    • सर्वान + शूद्रान् → सर्वाञ्छूद्रान्
20. Before ल-, न् becomes nasalized –ंल. (Hart 17)
    • तान + लोकान् → तांल्लोकान् (or less often, तांलोकान्).
21. Before unvoiced palatal and dental stops (च-, छ-, त-, थ-) a sibilant of those classes (i.e. श, स) is inserted after –न, and –न becomes anusvāra. (Hart 18)
    • देवान् + च → देवांश्च
    • नृपान् + तत्र → नृपांस्तत्र
22. Before any voiced sound (vowel, diphthong, voiced consonant, and ह-), –त becomes –द, प् → ब् and –क् → –ग् . If the initial letter of the next word is ह-, the ह– becomes ध-.5 (Hart 19)
    • एतत् + हि → एतद्धि
    • अदत् + एव → अददेव
23. Before ल-, –त् become –ल्. (Hart 20)
    • मुखात् + लभते → मुखाल्लभते
24. Before the lingual and dental sibilantsष्andस्, finalनremains unchanged, but aत्may also be inserted between the nasal and the sibilant. (Whitney §207, p.69)
    • तान् षत् → तान्त्षत्
    • महान् सन् → महान्त्सन्
25. Before च-, छ-, and श-, –त् becomes –च्. If the next letter is श-, the श– becomes छ-. (Hart 21)
    • वृक्सात् + छाया → वृक्शाच्छाया
    • तस्मात् + च → तस्माच्च
    • नृपात् + शमः → नृपाच्छमः
26. Before ज-, –त् becomes –ज्. (Hart 22)
    • गृहात् + जलम् → गृहाज्जलम्
27. Before nasals, –त् becomes –न्. (Hart 23)
    • गृहात् + नयति → गृहान्नयति
28. Dental –न– inside a word when preceded by ऋṛ, ऋृ ṝ, र r, or षṣ and immediately followed by a vowel or by –न-, –म-, –त-, or –व– becomes a retroflex –ण– unless there intervenes a palatal (except य), a retroflex or a dental. (Hart 24)6
    • Inst. sg. of ग्राम is ग्रामेण
    • Gen. pl of शूद्र is शूद्राणाम्
    • Gen. pl of मनुष्य is मनुष्याणाम्
    • Inst. sing. of क्षत्रिय is क्षत्रियेण
    • Inst. sg. of नृप is नृपेण
    • But inst. sg. of रथ is रथेन
29. –न् occurring as a final after a short vowel is doubled before an initial vowel. (Hart 25).
    • तिष्ठन् + अत्र → तिष्ठन्नत्र
    • तस्मिन् + अपि → तस्मिन्नपि
30. In general, छ– is not allowed to stand after a vowel but becomes च्छ-. (Hart 26)
    • सा + छाया → सा च्छाया
31. Non-final स becomes ष if immediately preceded by any vowel except अ or आ, or if precede by क or र, unless the स is final or followed by र. (Hart 27)
    • Reduplication of स्था is तिष्ठति
    • Loc. pl of देव is देवेषु but loc. pl of सेना is सेनासु
32. A voiced non-nasal stop cannot stand at the end of an utterance, but must be converted to its unvoiced equivalent. (Hart pp. 30-31, not numbered)
    • पाद् → पात्
    • त्वच् → त्वक्
    • वणिज् → वणिक्
33. The only permitted final consonants are –क्, –ट्, –त्, –प्, –ञ्, (-ण्), (-न्), –म्, (-ल्), -: Other final consonants are converted in the following way (Hart pp. 31-32):
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    

    –च्	–क्
    –ज्	–क् / –ट्
    –श्	–क् / –ट्
    –ष्	–ट्
    –ह्	–क् / –ट्

    
    
34. Saṃdhi of –क and –ट. Before a nasal, –ट → –ण, –क → ञ. Before voiced sounds, ट → ड and –क → –ग. Before ह-, –ट → –ड and –ह becomes –ढ; –क → –ग and –ह becomes –घ. (Hart, p. 32)
    • विराट् + न → विराण्न
    • वाक् + मे → वाञ्मे
    • वाणिक् + ददाति → विणिग्ददाति
    • हव्यवाट् + आगच्छति → हव्यवाडागच्छति
    • प्रावृट् + हि → प्रावृड्ढि
    • वणिक् + हि → वणिग्घि
35. The pronoun सः (nom. masculine singluar) loses the final –स् before all consonants, but not before vowels:
    • सः गच्छति → स गच्छति
    • सः अगच्छत् → सोऽगच्छत्
36. The imperfect augment अ– added to the initial vowel of verb stems, इ-, उ-, and ऋ– coalesces to make the vṛddhi (not the guṇa) of the second element, that is ऐ-, औ-, and आर-. The rule applies to both thematic and athematic verbs (Hart, p. 78)
37. When a voiced aspirate is followed by an unvoiced character (either aspirate or non-aspirate), the first voiced aspirate becomes its corresponding voiced non-aspirate, and the second character turns into its corresponding voiced aspirate. (Hart, p. 128)7 Thus,
    • बुध् + –त → बुद्ध
    • लभ् + –त → लब्ध
    • दोह् + –ति → दोघ्‌8 + ति → दोग्धि (3^rd person singular present active of दुह्)
38. A dental –त when it immediately follows a –ष्– is retroflexed. (Hart, p. 128) Thus,
    • तुष् + त → तुष्ट
39. Grassman’s Rule: If two aspirated consonants occur in the same syllable, the first one looses its aspiration. However, in certain situations (particularly when followed by a sibilant)9 the second aspiration is “lost” before this rule is applied so that the first retains its aspiration. Thus, the 2^nd person singular present of दुह् is धोक्षि but the 2^nd person plural present is दुग्ध. (The difference in the vowel is due to the strong and weak forms of the verb, not related to this rule.) (Hart, p. 32)

 

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