This is a companion discussion topic for the original entry at https://english.best/questions/3414,he-tends-to-forget-things-very-quickly-and-behaves-more-and-more-like-the-typical-___-professor/
He tends to forget things very quickly and behaves more and more like the typical clear-minded professor.
My answer is wrong.
Absent-minded means they forget things. It’s not bad memory about things from the past. For example they have a 10:00 appointment and completely forget about it. The memory is still there, but they don’t remember until four hours later. Or they weren’t paying attention when they set something down, then later can’t remember where they put it.
“Absent-minded professor” is a little more than that. They are someone who is very intelligent, but they are absent-minded because they are so focused on intellectual thoughts. They may forget to do things. They may not notice things going on around them. Someone may say something to them, but they are focused on something else and not paying attention.
An absent minded professor does not have to be a professor, but it always means someone intelligent.
Many thanks NearlyNapping.