Pronounced: PIN-der, noun
Notes: This is a word I’ve never heard (that I know of); I ran across it while reading the definition of another word
The word hebetude means “lethargy, dullness”.
This word comes from Late Latin hebetudo (dullness, bluntness). This derives from the Latin root hebes (dull).
The word first showed up in the early 1600s
I knew the meaning of inane, so it didn’t make the cut