迟钝 (chí dùn): slow in one's reactions; sluggish (in movement or thought)

He is a bit slow to react; several seconds after others finished telling a joke, he finally laughed out loud.

As she has grown older, Grandma's hearing has become somewhat dull, so we have to speak to her a little louder.

When I first learned to drive, my judgment of road conditions was rather slow; I often had to wait until the last moment to brake.

This little dog seems very slow to respond to its owner's call; only after several calls did it slowly come over.

She is slow to catch on in math, but as long as she spends more time practicing, she can gradually catch up with her classmates.