Sanskrit has inherited from its reconstructed parent the Proto-Indo-European language an elaborate system of nominal morphology. Endings may be added directly to the root, or more frequently and especially in the later language, to a stem formed by the addition of a suffix to it.
Sanskrit is a highly inflected language that preserves all the declensional types found in Proto-Indo-European, including a few residual heteroclitic r/n-stems.
Basics
Declension of a noun in Sanskrit involves the interplay of two 'dimensions': three numbers and eight cases, yielding a combination of 24 possible forms, although owing to syncretism of some forms, the practical number is around 18 or so. Further, nouns themselves in Sanskrit, like its parent Proto-Indo-European, can be in one of three genders.
In addition, adjectives behave much the same way morphologically as nouns do, and can conveniently be considered together. While the same noun cannot be seen to be of more than one gender, adjectives change gender on the basis of the noun they are being applied to, along with case and number, thus giving the following variables:
Building blocks
Roots
The oldest system of declension was to affix the endings directly to the nominal root. This was an ancient feature already in decline in later Proto-Indo-European. Of the daughter languages, this system has been best preserved by Sanskrit, especially the older form of Indo-Aryan termed Vedic Sanskrit.
Stems
In Proto-Indo-European, a new system developed wherein an intermediary called the thematic vowel is inserted to the root before the final endings are appended: *-o- which in Sanskrit becomes -a-, producing the thematic stem.
Declension of a thematic stem is less complicated owing to the fact that a host of Sandhi rules apply no more, and the later stages of the Sanskrit language see an increase in the profusion of thematic nouns. Thus in classical Sanskrit, the thematic pā́da-s is more likely to be found than its athematic predecessor.
Cases
Sanskrit nouns are declined for eight cases:
nominative: marks the subject of a verb. accusative: used for the direct object of a transitive verb. instrumental: marks the means by which the subject achieves or accomplishes an action, physically or abstractly. dative: used to indicate the indirect object of a transitive verb. ablative: used to express motion away from something. genitive: marks a noun as modifying another noun. locative: corresponds vaguely to the English prepositions in, on, at, and by. vocative: used for a word that identifies an addressee.
The kāraka classification
In the ancient literature, Pāṇini identified six classes as kārakas, operating as accessories to a verb. The six kārakas are the nominative, accusative, instrumental, dative, ablative, and locative cases. He defined them as follows (Aṣtādhyāyi, I.4.24–54):
Kartā : 'he/that which is independent in action'. This is equivalent to the nominative case. Karman : 'what the agent seeks most to attain': the accusative. 'that which effects most': the instrumental. Sampradāna : 'he whom one aims at with the object': the dative. Apādāna : '(that which is) firm when departure (takes place)': the ablative. : or 'substratum': the locative.
Pāṇini did not identify the genitive Sambandha and vocative Sambodhana as kārakas.
Endings
The basic scheme of suffixion is given in the table below and applies to many nouns and adjectives.
However, according to the gender and the final consonant or vowel of the uninflected word-stem, there are internal sandhi rules dictating the form of the inflected word. Furthermore, these are standalone forms, which when used in actual phrases are subject to external sandhi, such as, the mutation of -s to -ḥ or -r and so on.
Declension
Classification
Substantives may be divided into different classes on the basis of the stem vowel before they are declined on the above basis. The general classification is:
Short-vowel stems
a-stems
i- and u-stems
ṛ-stems
Long-vowel stems
ā-stems
ī- and ū-stems
Diphthong stems
Consonant stems
Bare stems
as/is/us-stems
an- and in-stems
ant-/mant-/vant-stems
vāṅs-stems
When the nominal endings are being affixed to a noun of each class, they may undergo, in some cases, some changes, including being entirely replaced by other forms. This happens most profusely in the a-stem class. However, for reasons noted below, grammars both traditional and modern tend to start with this class.