abstruser
adj. C2 Proficiency ab·struser
adj. more difficult to understand or more strange than something else. It is an old-fashioned word that people rarely use today.
adj. more difficult to comprehend or more obscure in meaning.
The second chapter was more abstruse than the first.
The philosopher's later works became increasingly abstruse, making them difficult for even his most dedicated students to follow.
While the initial theory was clear and logical, the subsequent mathematical proofs were so abstruse that they required years of specialized study to fully grasp.