Meaning -  KaThopanishad. S.B. Introduction--- saderdhatoH vis'araNa---- vidyaa uchyate. The word `Upanishad' is derived by adding the prefixes `upa' (near) and `ni'
(with certainty) and the suffix `kvip' to the root `sad' meaning ` to destroy, to go to and
to loosen'. By the word 'Upanishad' is meant the knowledge that destroys the seeds of worldly existence such as ignorance in the case of those seekers of liberation who, after cultivating detachment towards all enjoyments, approach (upa,sad) this knowledge and
then deliberate on it with steadiness and certainty (ni).

    Though this knowledge is the primary meaning of the word, it is used also to denote
the book that contains this knowledge, in a secondary sense. Br.up.1.1.S.B.Introduction-saa iyam brahmavidyaa ----upanishad uchyate. The
knowledge of Brahman is called 'upanishad' because it entirely removes this relative
world together with its cause from those who take to this study; for the root 'sad'
prefixed by 'upa' and 'ni' means that. Books also are called 'upanishad' as they have
the same end in view. There is no contradiction between the upanishads and the
ritualistic portion (karma kanda) of the Vedas. Br.up.2.1.20.S.B-tasmaat na brahmaikatvam-------------------- -------- pramaaNaani s'rotraadivat.

    Therefore the Vedaanta texts that teach the oneness of Brahman are not antagonistic
to the ritualistic portion. Nor are the latter deprived of their scope by the former.
Neither do the ritualistic scriptures, which are based on differences such as the factors
of an action, take away the authority of the upanishads as regards the oneness of Brahman. For the means of knowledge are powerful in their respective spheres, like
the ear, etc. The ritualistic portion of the Vedas ceases to apply only
after a person has attained Self-knowledge and has become liberated.