निःशब्दपदम्niḥśabdapadamind. with soundless i.e. inaudible steps R.
indeclinable with soundless id est inaudible steps R.
कोशःDictionaries
Every entry for a word in Apte, Monier-Williams, Macdonell and the Dhātupāṭha, with their abbreviations spelled out, and an analysis of its forms.