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.
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.
Verb conjugation in Sanskrit involves the interplay of five 'dimensions', number, person, voice, mood and tense, with the following variables:
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.
Classical Sanskrit has only one infinitive, of accusative case-form.
The starting point for the morphological analysis of the Sanskrit verb is the root. It is conventionally indicated using the mathematical symbol âÂÂ; for instance, "âÂÂbhà «-" means the root "bhà «-".
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.
Before the final endings â 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.
The following types of treatment are possible on the root to form the stem:
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 guá¹Âa 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.
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-, -nÃÂ-, and -aya-. Of these the first and the last include the thematic vowel while the others are athematic.
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, á¹Â, á¹ ), while in strong forms this expands to -ná- and bears the accent.
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 guá¹Âa or vá¹Âddhi, 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 guá¹Âa 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.
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:
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 á¹Â, the vowel is subject to vá¹Âddhi and not guá¹Âa.
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.
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.
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:
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.
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 or gaá¹Âas, 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: