The word tiras 'disappearance' is optionally called gati when the verb kṛ follows.,
This is an example of प्राप्त-विभाषा. As तिरः कृत्य or तिरस्कृत्य 8.3.42: तिरः कृत्वा or तिरस्कृत्वा 8.3.42. The change of visarga into स is optional 8.3.42. When not meaning disappearance we have तिरः कृत्वा काष्ठं तिष्ठति he stands having laid aside the stick.,