Vṛddhi
Vṛddhi (Sanskrit:वृद्धि, IPA: [ˈʋr̩d̪d̪ʰi]) is a Sanskrit word meaning 'growth' (from Proto-Indo-European *werdʰ- 'to grow').
In Pāṇini's Sanskrit grammar, it is a technical term for long vowels produced by ablaut (vowel gradation), as for example in: