Dear Student,
1.The word 'Upanishad' simply means 'sitting closer' or 'sitting near' and suggests listening closely to the mystical doctrines of a guru or a holy teacher who has come to realise the universal truths of the universe.
2.The literal sense of upanishad, "sitting near devotedly," brings a stern disciple to mind when he hears from his tutor. The term also means "secret teaching"—secret, no doubt, and the teaching is true only for those who are spiritually able to receive and prosper from it.
I hope the answer will serve your purpose
Regards