Obtuse – not quick or alert in perception, feeling or intellect; not sensitive or observant. Dull.
I had forgotten about this word until I heard it recently. I use it whenever I am able. For some unknown reason I forgot the word today. I walked around trying to recall it but I came up short. How could I forget it so soon. I asked the young people if they recalled the word. To my surprise one of them produced the word. Sometimes they do listen!