I started thinking about these two verbs the other day after seeing a reference to one of them in a technical document.

I saw a reference to the verb “black”, which dates back to the 1200s, in an IPTV technical document.

The document referred to a “blacked screen.”

The transitive verb “black” means to make black.

The intransitive verb “black” means to become black.

Now consider the verb “blacken”, which dates back to the 1300s.

The transitive verb “blacken” primarily means to make black or to darken and secondarily means to sully or defame.

The intransitive verb “blacken” means to become black or dark.

For example, “blackened chicken” and “blackened salmon” and “blackened tuna”, which are popular American menu items now, are not completely black.

So it seems that one can blacken the flesh of animals used as food and can black a TV screen, but not the other way around.