Obtuse can mean slow to understand something, or deliberately difficult when someone is trying to explain something. When someone is being obtuse, they either genuinely don't get what you're saying, or they're pretending not to understand to avoid doing what they've been asked.

Imagine explaining to your friend how to solve a math problem, and they keep saying “I don't get it” about the simplest steps, even though you know they're perfectly capable of understanding. They might be acting obtuse. Or picture a student who keeps asking “why?” over and over about obvious things when the teacher is trying to move the class forward.

The word comes from geometry, where an obtuse angle is one that's wider than 90 degrees, making it look dull or blunt rather than sharp and pointed. Just as an obtuse angle isn't sharp, an obtuse person isn't being mentally sharp in that moment.

Being obtuse is different from being confused or needing extra help. When someone is genuinely struggling, they ask specific questions. When someone is being obtuse, they resist understanding, either because they're distracted, being stubborn, or hoping the problem will go away if they act confused enough.