Upanishad or upanishabth meaning

Many has defined the term "Upanishad" in literary and word formation sense as "brahma vidhya" ie. knowledge of supreme self. It's observation of the individual who had known the supreme self. Upa-ni-shabdh aslo means the same. Upa means nearness , closeness, alternative etc. and nishabdh means silence. There are some reference to Upanishabdh also by writers as "Nearness to silence". "Ni" also means for ragam nishadam which related to root chakra, it also correspond to vital force cause source of thought.