Gnanavarniya (Jñānāvaraṇīya) karma means “knowledge‑obscuring karma.”

Simple definition:

• Every soul (jiva) has natural, infinite knowledge.
• When very subtle karmic particles of the Gnanavarniya type bind to the soul, they cover or veil this knowledge, so the soul cannot fully know or understand.
• It does not destroy knowledge, it only blocks its manifestation, like a cloud covering the sun.

Because of Gnanavarniya karma:

• We forget things.
• We misunderstand or cannot grasp teachings.
• Even higher kinds of knowledge (like clairvoyance or keval‑jnan) are obstructed.

It is one of the four Ghati (destructive) karmas, accepted in both Śvetāmbara and Digambara traditions.

Five sub‑types (it can block each type of knowledge):

1. Mati‑jnanavarniya – obscures sense‑based knowledge (through mind and senses).
2. Shrut‑jnanavarniya – obscures scriptural / verbal knowledge.
3. Avadhi‑jnanavarniya – obscures limited clairvoyant knowledge.
4. Manahparyaya‑jnanavarniya – obscures telepathic knowledge.
5. Keval‑jnanavarniya – obscures omniscience (perfect knowledge).

To destroy Gnanavarniya karma, Jain Dharma teaches:

• Right faith (samyak darshan)
• Right knowledge (samyak jnan)
• Right conduct (samyak charitra)
• Tapas (austerities) and careful avoidance of sins of mind, speech and body.

You can read a simple explanation of this karma here