contranym

Same as autoantonym.

A contranym, sometimes called a "Janus word," can take on either of two opposite meanings. I made a list of my 'favorrite' ones here.

What, you mean "transparent" used to mean "someone can easily see how this works"? I would say it has a toehold on contranymity, as a non-opaque item would be harder to see and understand than an opaque one.

And what about transparent, as in user transparent? Not quite a contranym, yet peculiar to me, a non-technical person. (I am, however, technically a person)

cleave
sanction