Sanskrit has, together with Ancient Greek, kept most intact among descendants the elaborate verbal morphology of Proto-Indo-European. Sanskrit verbs thus have an inflection system for different combinations of tense, aspect, mood, voice, number, and person. Non-finite forms such as participles are also extensively used.Fortson, §10.41.Whitney p. 200 ch. 8.
Some of the features of the verbal system, however, have been lost in the classical language, compared to the older Vedic Sanskrit, and in other cases, distinctions that have existed between different tenses have been blurred in the later language. Classical Sanskrit thus does not have the subjunctive or the injunctive mood, has dropped a variety of infinitive forms, and the distinctions in meaning between the imperfect, perfect and aorist forms are barely maintained and ultimately lost.Macdonnell, Vedic p.118.Fortson, §10.41.
Basics
Verb conjugation in Sanskrit involves the interplay of five 'dimensions', number, person, voice, mood and tense, with the following variables:Bucknell, p. 34.
+ 1 3 numbers singular, dual, plural 2 3 persons first, second, third 3 3 voices active, middle, passive 4 4 moods indicative, optative, imperative, conditional 5 6 tenses present, imperfect, perfect, aorist, periphrastic future, simple future
Further, participles are considered part of the verbal systems although they are not verbs themselves, and as with other Sanskrit nouns, they can be declined across seven or eight cases, for three genders and three numbers.Burrow, p. 367
Classical Sanskrit has only one infinitive, of accusative case-form.Whitney, §538
Building blocks
Roots
The starting point for the morphological analysis of the Sanskrit verb is the root. It is conventionally indicated using the mathematical symbol √; for instance, "√bhū-" means the root "bhū-".
There are about 2000 roots enumerated by the ancient grammarians, of which less than half are attested in actual use. Allowing for sorting reduplication and other anomalies, there remain somewhat over 800 roots that form the practical basis of the verbal system, as well as the larger part of the inherited nominal stems of the language.
Compared to kindred Indo-European languages, Sanskrit is more readily analysable in its morphological structure, and its roots are more easily separable from accretionary elements.Burrow, §7.1.
Stems and stem formation
Before the final endings — to denote number, person etc can be applied, additional elements may be added to the root. Whether such elements are affixed or not, the resulting component here is the stem, to which these final endings can then be added.Burrow, §7.3.Whitney, ch 8.
The following types of treatment are possible on the root to form the stem:
No Treatment
The personal endings are directly affixed to the root with no prior modification, subject to any internal sandhi rules in the process. With a few exceptions, the root keeps the accent and guṇa grade in the three persons of the active, while elsewhere the termination takes on the accent and the root grade is weakened.
There are around 130 roots in Sanskrit that come under this class. Sanskrit is unique among the ancient Indo-European languages to have largely preserved this system, which has largely died out in the others. Since adding endings to the root is complicated by phonological changes, the tendency right from the Proto-Indo-European stage has been to use thematic processes instead.Burrow, §7.8
Suffixation
A theme vowel is suffixed before any personal endings are added. In Sanskrit, this is -a-, inherited from Proto-Indo-European and . The addition of the theme vowel serves to avoid complications due to internal sandhi; the large majority of the verbs in the language are thematic.
Sanskrit also inherits other suffixes from Proto-Indo-European: -ya-, -ó- / -nó-, -nā-, and -aya-. Of these the first and the last include the thematic vowel while the others are athematic.
Infixation
Another treatment also from Proto-Indo-European is inserting an exponent within the root itself. All roots undergoing this treatment end in consonants. In weak forms, the infix is simply a nasal (n, ñ, ṇ, ṅ), while in strong forms this expands to -ná- and bears the accent.Whitney, §683
Accent and gradation
During conjugation, the accent might fall either on the root vowel or on the ending. Among thematic verbs, some roots always get the accent, accompanied by a strengthening of the grade to guṇa or vṛddhi, while in others it always falls on the ending. In non-thematic cases, the position of the accent varies.
The general rule for variable-accent verbs is that in the indicative the stem has the accent and the guṇa grade in the three persons of the singular active, and that in the dual and plural of the active and the whole of the middle, the accent falls on the ending and the stem is in its weak form.Burrow, §7.5
Reduplication
The root might be subject to reduplication, wherein a part of it is prefixed to itself in the process of forming the stem. For roots beginning in a consonant, that initial consonant, or a modified form of it, is taken, while for those beginning in a vowel, it's the very vowel.
The potential modifications that might be made to the prefix consonant can be seen in some typical examples below:Whitney, §588–590.
+ Reduplication patterns Root Reduplication Remarks √budh- bu·budh- standard √śru- śu·śru- √dhā- da·dhā- aspirate → non-aspirate √kṛ- ca-kṛ guttural → palatal √khid- ci·khid- √grabh- ja·grabh- √hṛ- ja·hṛ- √stṛ- ta·stṛ- second consonant in a cluster √sthā- ta·sthā- √skand- ca·skand- a combination of above rules
Augment
Roots are prefixed with an á- (from PIE é-) in preterite formations (imperfect, aorist, pluperfect, conditional). The augment without exception bears the accent in these forms. When the root starts with any of the vowels i-, u- or ṛ, the vowel is subject to vṛddhi and not guṇa.Burrow, §7.5.Whitney, §585.
icch·á·ti -> aí·cch·a·t urṇó·ti -> aú·rṇo·t ṛdh·nó·ti -> ā́r·dh·no·t
Voice
Sanskrit has in the present inherited two sets of personal endings from its parent Proto-Indo-European, one for the active voice and another for the middle voice. Only some verbs can be conjugated in either voice, most verbs only show one or the other.Burrow, §7.6
Originally the active voice suggested action carried out for someone else and the middle voice meant action carried out for oneself. By the time of Classical Sanskrit, and especially in later literature, this distinction blurred and in many cases eventually disappeared.Burrow, §7.6Macdonnell, ch. 4.Whitney, ch. 8, §528–531.
Personal endings
Conjugational endings in Sanskrit convey person, number, and voice. Different forms of the endings are used depending on what tense stem and mood they are attached to. Verb stems or the endings themselves may be changed or obscured by sandhi. The theoretical forms of the endings are as follow:Bucknell, p. 43.Whitney, §553
Active Middle Person Singular Dual Plural Singular Dual PluralPrimary 3 -ti -tás -ánti, -áti -té -ā́te -ánte, -áte 2 -si -thás -thá -sé -ā́the -dhvé 1 -mi -vás -más -é -váhe -máheSecondary 3 -t -tā́m -án, -ús -tá -ā́tām -ánta, -áta, -rán 2 -s -tám -tá -thā́s -ā́thām -dhvám 1 -am -vá -má -í, -á -váhi -máhiPerfect 3 -a -átus -ús -é -ā́te -ré 2 -tha -áthus -á -sé -ā́the -dhvé 1 -a -vá -má -é -váhe -máheImperative 3 -tu -tā́m -ántu, -átu -tā́m -ā́tām -ántām, -átām 2 -dhí, -hí,— -tám -tá -svá -ā́thām -dhvám 1 -āni -āva -āma -āi -āvahāi -āmahāi
Primary endings are used with present indicative and future forms. Secondary endings are used with the imperfect, conditional, aorist, and optative. Perfect and imperative endings are used with the perfect and imperative respectively.
Verb classes
Based on the treatment they undergo to form the stem, the roots of the Sanskrit language are arranged by the ancient grammarians in ten classes, called , based on how they form the present stem, and named after a verb typical to each class.
No discoverable grammatical principle has been found for the ordering of these classes. This can be rearranged for greater clarity into non-thematic and thematic groups as summarized below:Whitney, ch. 8.Monier Williams – word meanings
+ Thematic verb classes Root Treatment Stem Conjugation samples Remarks √bhū- Root accent, gunated bháv- First bháv·a·ti The commonest of all classes, with nearly half of the roots in the language.Burrow, p. 328 √tud- None (ending accent) tud- Sixth tud·á·ti √dív- -ya- suffix dī́v·ya- Fourth dī́v·ya·ti √cur- -aya- with root gradation, or -áya- without cór·aya- Tenth cór·aya·ti Usually to form causatives, not strictly a class per seWhitney, §775
+ Athematic verb classes Root Treatment Stem gaṇa Conjugation samples √ad- None ad- Second at·ti at·tas ad·anti √hu- Reduplication, accent varies juhó- juhu- júhv- Third juhó·ti juhu·tás júhv·ati √su- -no- suffix su·nó- su·nu- su·nv- Fifth su·nó·ti su·nu·tás su·nv·ánti √tan- -o- suffix tan·ó- tan·u- tan·v- Eighth tan·ó·ti tan·u·tás tan·v·ánti √krī- -nā- suffix krī·ṇā́- krī·ṇī- krī·ṇ- Ninth krī·ṇā́·ti krī·ṇī·tás krī·ṇ-ánti √rudh- Nasal infix ru·ṇá·dh- ru·n·dh- Seventh ru·ṇá·d·dhi ru·n·d·dhás ru·n·dh·ánti
and roots
Sanskrit roots may also be classified, independent of their , into three groups, depending on whether they take the vowel before certain tense markers. Since the term used for this vowel by Sanskrit grammarians is , these two groups are called (with ), (optional ), and (without ), respectively.Fortson, §4.7.Meier-Brügger et al.The Astadhyayi of Panini
The i sound in question is a phoneme i that appears in certain morphological circumstances for certain, lexically defined roots, regularly continuing Proto-Indo-European (PIE) laryngeals, as in > bháv·i·tum. Note that the PIE laryngeal (represented by an here) was a part of the PIE root; it occurs in all of its allomorphs, for example > bhū·tá·s ( is reduced to in PIE due to ablaut; the laryngeal disappears in this context, leaving its trace in the length of ū in Sanskrit). In Classical Sanskrit, the scope of this i was broadened by analogous change.
In the Aṣṭādhyāyī the synchronic analysis of the phenomenon is somewhat different: the i sound is treated as an augment of the suffix that follows the root. Rule 7.2.35 states that i should be prepended to ārdhadhātuka suffixes beginning with a consonant other than y; an example of such suffix is -tum (the Classical Sanskrit infinitive).
An example of differences between the two classes is the aorist-marker. While some of the aniṭ-roots form aorist with the -s suffix, seṭ-roots are suffixed by -iṣ.
Following this terminology, PIE roots ending in laryngeals are also called seṭ-roots, and all others aniṭ-roots.
Conjugation
Scope As in kindred Indo-European languages, conjugation is effected using the above building blocks across the tenses, moods, voices, persons and numbers, yielding, in Sanskrit, a huge number of combinations.
Where the forms take personal endings, in other words when it complements a subject, these are called finite forms. Sanskrit also has a few subjectless, i.e., non-finite forms. In the standard scenario, the following forms are seen in Classical Sanskrit:Whitney, §527–541.Bucknell, §2.B.
+ Conjugation – standard finite verbsWhitney, §527–541. System Tense Mood Endings Conventional term Present Present Indicative Primary 'Present' Optative Secondary 'Optative' Imperative Imperative 'Imperative' Imperfect Indicative Secondary 'Imperfect' Perfect Perfect Indicative Perfect 'Perfect' Aorist Aorist Indicative Secondary 'Aorist' Precative Optative Secondary 'Precative' Future Future Indicative Primary 'Future' Conditional Secondary 'Conditional' Periphrastic Indicative Secondary 'Periphrastic'
Furthermore, Sanskrit has so-called Secondary conjugations:Whitney, §540.
Passive Intensive Desiderative Causative Denominative
The non-finite forms are:
Participles