snātvyī etc. are irregularly formed in the chandas (Vedas).,
Thus स्नात्वी मलादिव, for स्नात्वा; पीत्वी सोमस्य वावृधे for पीत्वा ॥ The word आदि 'et cetera' means \of the form of\, namely words having form like स्नात्वी, as पीत्वी &c.,
स्नात्व्यादयश् च
Adhyāya 7 · Pāda 1 · Rule 49