Un- vs Dis-, are there any semi-uniform rules for what each means in context?

Most times when you learn about the prefixes un- and dis- you learn that they’re the same, they both mean “not.” However, as I think a lot of us have noticed, that’s not quite the case. For instance, “undone” doesn’t mean “not done” it means “reversed.” I can’t think of a “standard” word that does this off the top of my head (though I’m pretty sure there is one), but take the neologism “unlike”, it’s different from “dislike”. Whereas “dislike” is to “not like” something, “unlike” is closer to “I used to like it, but now I don’t”.

Yet still there are words like unable vs disable, where the usage is almost reversed. Unable means you cannot do something, the verb “to disable” means essentially to reverse or take away the ability to. Even still, we have “uncolor” which means to reverse or remove the color, and “discolor” which means to smear or generally make the color different. “Uncolor” would imply going from color to a white/black/greyscale, and “discolor” would imply going from a color to a different (implied unusual or unwanted) color, or white/black/greyscale to a(n implied unusual or unwanted) color.

So what are the rules for their use? Are they a bunch of prefixes that merged somewhere down the line? Does it have to do with the linguistic origin of the root? Part of speech dependency? Is it just completely arbitrary? Is there any sense of rules governing when each prefix means what at all? I’d also be interested in hearing where “a-” fits into the scheme, though I’m pretty sure that one just has to do with the linguistic origin of the root (a- would fit in Greek roots I think).

I’m not disagreeing with your general observations, but I think “undone” can indeed mean “not done.” For instance, many Christian denominatinos have a prayer for forgiveness that includes lines like:

FWIW, I believe that un- is anglo-saxon in origin, while dis- comes from French (and yes, I think a- and an- are from Greek). My guess would be that there are no rules left for the distinctions by this time, as meanings have accreted and changed over centuries.

It also depends on the root word. The OP’s use of “Like” is a good case. Dislike relies on the word “like” meaning to enjoy. Unlike relies on the word “like” meaning a similarity. Also, Dislike is a verb and Unlike is an adjective.

If I get put on trial, I was a disinterested judge, not an uninterested one.
The meanings aren’t opposite, but they are different.

You was?

Gaudere lives!

well, consider the act of friending some1 on Facebok - then u don’t want them as a friend anymore. Wouldn’t ‘unfriend’ sound better than ‘disfriend’? Personally, I like ‘defriend’. But, from that example of friending, ‘friend’ is a verb. On the other hand, u can like someone, or dislike them. So maybe ‘un’ for active verbs, ‘dis’ for more descriptive ones? Similarly, consider untied, unmasked, unhanded, unpacked vs. disgruntled, disenfranchised, discombobulated, disoriented. Of course there’ll be exceptions, like disconnected (as a pasttense verb), & unstable but what language rule ain’t got violations? The whole topic is unruly (or disruly ?) :slight_smile: