The professor's lecture on quantum physics was so abstruse that most of the students couldn't follow.

He explained the concept abstrusely.

The abstruseness of the concept made it difficult for me to understand.

The abstrusenesses of the ancient text made it difficult to decipher.

The concept of quantum mechanics can be abstruser for beginners.

The abstrused concept was difficult to understand.

He used abstrusion to push the door open.

The abstrusity of the ancient text made it difficult to decipher.

The abstrusities of the ancient text were difficult to decipher.

The abstrusions in the artwork added depth and complexity.