Vijnanamaya means composed of vijnana, or intellect, the faculty which discriminates, determines or wills. Chattampi Swamikal defines vijnanamaya as the combination of intellect and the five sense organs.
Vijnanamaya kosha is the sheath where subtle intelligence evolves, where the four aspects of mind originate in their pure form, born of mahat or supreme intelligence.
From here we come to vijnanamaya kosha. 'Jnana' means 'wisdom', 'knowledge'; the prefix 'vi' is a confirmation of the intensity of knowledge which is derived not only from the experiences and memories which we have gained in this lifetime, but also in past lives.
Pranamaya Kosha, Manomaya Kosha and Vijnanamaya Kosha are in the astral body (Sukshma Sarira). Anandamaya Kosha belongs to the causal body (Karana Sarira). Pranamaya Kosha contains the five Karma Indriyas. Manomaya and Vijnanamaya Koshas contain the five Jnana Indriyas.
the energy and subtle bodies are capable of holding more of a charge (the current carrying capacity of the conduit is increased), while the foundational, but previously dormant circuitry (nadis), become activated, thus animating all four koshas (annamaya, pranamaya, manomaya, and vijnanamaya koshas).
The last layer of the subtle body is the wisdom body, the Vijnanamaya kosha. Vijnana means "knowledge" as this sheath contains intuition, wisdom and witness consciousness.
Vedanta says that the individual soul is enveloped by five sheaths"Annamaya Kosha (the gross body), Pranamaya Kosha (vital sheath), Manomaya Kosha (the mind), Vijnanamaya Kosha (the intellect), and Anandamaya Kosha (the bliss-sheath or the ignorance that immediately veils the Self), ...
My Annamaya Kosha is relaxing.
My Pranamaya Kosha is relaxing.
My Manomaya Kosha is relaxing.
My Vijnanamaya Kosha is relaxing.
My Anandamaya Kosha is relaxing.
See also: What is the meaning of Vijnana, Mind, Prana, Annamaya kosha, Body?