What does the term 'obtuse' refer to in terms of understanding?

The term 'obtuse' in the context of understanding indeed refers to being slow to learn or understand. In everyday language, when someone describes a person as obtuse, they often mean that the person is not quick to pick up on ideas or may struggle to comprehend information that is presented to them. This aligns with the notion of a lack of sharpness—much like an obtuse angle in geometry, which is greater than 90 degrees but less than 180 degrees, suggesting something that is not pointed or sharp.

The other options suggest a level of eagerness or aptitude for learning, which is contrary to the meaning of 'obtuse'. Instead of demonstrating a quick grasp or clear understanding, the term emphasizes a delayed or hindered ability to grasp concepts and ideas. This makes the first choice the most appropriate definition of 'obtuse' in the context given.