Stretch your imagination:

"Dressing up" has nothing to do with "dressing down."

Can you think of other sets like that?

slow up == slow down

Clap on, clap off...oh, wait.

Come on! Come off (it).

Dressing up -- dressing down

Slow up -- slow down

These are two completely different categories. In the former there is pretty much no relation at all between the phrases and the latter are synonyms.

Bring up, in the sense of raising a topic. He brought up the matter of unequal access to natural resources.

Bring down, in the sense of stifling someone's good mood. He's constantly bringing me down whenever he sees me enjoying myself.

Throw up (sick)- throw down

Though where the up and down give synonymous meanings, that's interesting too.

chopping up a log after chopping the tree down!

getting it on .. getting off

(but then most anything can be made salacious)

So the verb part of the one should refer to something completely different than the other?, Wofa Ho?

{ basically my English is not up to this preposition stuff, to use and understand those littlest ones right is the hardest thing with foreign languages}

take on - take off
put on - put off
onset - offset
inset - outset
undertake - overtake
let on - let off

It's more that the parts look as if they should be opposites, but the wholes turn out to be completely unrelated. The incongruity makes you do a double-take.

It's part of the perils of using idiomatic language. (My ninth grade French teacher tried to cure us of literal translation by asking us to translate, word by word, the sentence "I was left behind." Snickers everywhere...)

Ah, I see... hard to find other ones.

He didn't want to be dressing down a bunch of rookies.
Seattle Times Jul 21, 2011


“Dressing up is the new cool, and dressing down is old school,” he continued.
New York Times Sep 7, 2011

It can have both the normal opposite and your unrelated meaning.

I see.."J'etais à gauche derrière" ;-)

so are the pairs similar to an oxymoron then Wofa

what about these...

not yet
not always
not ever

We had a Latin teacher with:

Ubi, ubi, sunt sub ubi.

Not exactly. The oxymoron is a self-contained opposite -- "jumbo shrimp."
These false opposites have the external appearance of opposites, but rather instead they are like two lines that don't even intersect, rather than going in the other direction.

full duplex (teletype transmission in both directions at the same time)
empty duplex (can't rent my apartment for love nor money)

Your other examples are negation rather than contradiction .

Excuse the off topic intermission. I see all these notifications of apparently spams in the list. Is there maybe a virus jumping around here? In your last post in this frase'
(can't rent my apartment for love nor money)The word money was a light blue link. I stupidly clicked on it and an advertisement popped up. The next minute it was gone.

Is this me my computer or is it this site? Scary.

take from - take to

Some of these have multiple usages which may or may not be false opposites, depending on how you interpret them.

The word "money" was a light blue link. I stupidly clicked on it and an advertisement popped up. The next minute it was gone.

That doesn't sound good. It's not linked/underlined on my display. I would guess it's local; if you have a virus checker, run it.

"...apparent spams on the list" -- what list is that?

Or the more compact (if somewhat grammatically inconsistent) "Semper ubi, sub ubi". But these are homonym problems, not those other kinds.

That would be the active topic list, where the 'notified' means
a reported spam item.

In the meantime I have found out about the enhanced link problem. It is something called 'text enhance', very annoying but not malignant. By finding the distributers of the pest you can have yourself removed from their unwanted attentions.

Semper ubi, sub ubi - good! as long as "scis ubi"

false opposites:

undercoat = paint
overcoat = clothing

So can you give your overcoat a new undercoat?

Indeed.

Another pseudo-pair is upright/downright.

Pick up/put down... as in: He picked up the dog and put it down.

Look over/Overlook

Oversight/oversight.