In
Sanskrit grammar, one of the three
grades of the verb stem. The
zero grade is shortest,
guna is of middle length, and
vrddhi is the longest form of the stem vowel.
Short a becomes long â in vrddhi, i becomes ai (with intermediate guna e), and u becomes au (with guna o). The syllabic consonants r and l acquire a long â.
The name comes from the root vrdh, meaning grow.