उपपौर्णमासिupapaurṇamāsiमासम् [māsam], मासम् ind. just preceding or at the time of the full-moon day.
मासम् māsam, मासम् Indeclinable just preceding or at the time of the full-moon day.
कोशःDictionaries
Apte, Monier-Williams and Macdonell at once. Type in any of fifteen scripts and schemes; the word is converted and looked up wherever it is part of a headword.