Where Did Dumbing Down Originated?

Originated in 1933, the term "dumbing down" was movie-business slang, used by screenplay writers, meaning: "[to] revise so as to appeal to those of little education or intelligence".

What's the opposite of dumbing down?

In regards to a presentation, I think we generally "dumb down" information to make it more digestible for novices and neophytes; therefore, the opposite would be to design the presentation for experts, rather than for the masses.

What is the meaning of dumbing down?

transitive verb. : to lower the level of difficulty and the intellectual content of (something, such as a textbook) also : to lower the general level of intelligence in the dumbing down of society.