Vṛddhi (also rendered vr̥ddhi) is a technical term in morphophonology given to the strongest grade in the vowel gradation system of Sanskrit and of Proto-Indo-European. The term is derived from Sanskrit वृद्धि vṛddhi, in Sanskrit pronounced as /ˈʋr̩d̪ːʱi/, 'growth', from .[1]
Vṛddhi itself has its origins in proto-vṛddhi, a process in the early stage of the Proto-Indo-European language originally for forming possessive derivatives of ablauting noun stems, with the meaning "of, belonging to, descended from".[2] To form a vṛddhi-derivative, one takes the zero-grade of the ablauting stem (i.e. removes the vowel), inserts the vowel *e in a position which does not necessarily match that of the original vowel, and appends an accented thematic vowel (or accents any existing final thematic vowel). For example:
However, in a later stage of the language this appears to have extended to non-ablauting noun stems that already contained *e, which would contract with the inserted vowel to form a lengthened *ē:
The above example also displays the stressing of the thematic vowel when it already exists. It is this later version of proto-vṛddhi which is displayed in Sanskrit's lengthened vṛddhi grade.
The general phenomenon of vowel gradation, including vṛddhi formation, has been extensively studied and documented as part of Sanskrit's vigorous grammatical tradition, most importantly in the Aṣṭādhyāyī of the grammarian Pāṇini.[3]
For example:
The full pattern of vowel gradation can be observed as follows:[4]
| Zero grade | ← 1st grade → | 2nd grade | ||
|---|---|---|---|---|
| Open | ∅ | a | ā | |
| Palatal | i/ī y i/ī | e ay ya | ai āy yā | |
| Labial | u/ū v u/ū | o av va | au āv vā | |
| Retroflex | ṛ r ṛ | ar ar ra | ār ār rā | |
| Dental | ḷ | al | āl |
In modern Indo-European linguistics it is used in Pāṇini's sense and applied to the Indo-European languages in general. The feature is considered to have been inherited from the Proto-Indo-European language.