Which term relates to being subtle and not easily understood?

• A. Abstruse
• B. Infinitesimal
• C. Expiate
• D. Cognitive

Answer: (A)

Subtle and not easily understood describes ideas that are intricate and hard to grasp. Abstruse captures that sense: something abstruse is obscure, recondite, and requires careful thought to penetrate. You might see abstruse arguments in philosophy or dense mathematical proofs where the reasoning isn’t obvious at first glance. Infinitesimal means extremely small in size or amount, so it relates to quantity rather than understanding. Expiate means to atone for a wrongdoing, which is about making amends, not comprehension. Cognitive concerns mental processes like perception and thought, not the level of complexity in an idea.