AUSMACHEN!

The two most common meanings of the verb ausmachen are "to turn something off" and "to bring something to a conclusion with someone, to arrange something, or to agree on something." These are the first two definitions listed in the academic Digitales Wörterbuch der deutschen Sprache (DWDS) from the Berlin-Brandenburg Academy of Sciences and Humanities. Interestingly, both of these usages are listed as slang.

The commercial dictionary publisher Duden lists the two definitions as numbers one and three, respectively, but only lists the "turning off" definition as slang.

It does make you wonder: Should the most widely used version of a word still be considered slang?

TURN IT OFF!

Jetzt mach doch bitte mal den Fernseher aus!

Now please turn off the television!

Caption 12, Lerchenberg: Du bist, was du isst

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Ey DJ! DJ, mach die Musik aus!

Hey DJ! DJ, turn the music off!

Caption 70, Laserkraft 3D: Nein, Mann

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Was bedeutet es, wenn wir das Licht ausmachen?

What does it mean when we turn out the light?

Caption 56, Kinder lernen: Wie aus Wind Strom gemacht wird

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Aber ein Hund, ne? -Machen Sie die Kamera jetzt aus.

But a dog, right? -Turn the camera off now.

Caption 30, Kurzfilm-Festival: Nicht nur der Himmel ist blau

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A less informal way to ask somebody to turn a device off would be to use the verb ausschalten.

MAKE ARRANGEMENTS

Die Mitarbeiter stellen uns den Kontakt zu den jeweiligen Ansprechpartnern her, so dass wir alle nötigen Infos vorab schon einmal erfragen und die Drehtermine ausmachen können.

The staff puts us in touch with the respective contact person so that we can request all the necessary information in advance and set up the dates for the shoot.

Captions 10-12, Rund um den Airport: Hinter den Kulissen

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Und da haben wir auch, direkt auch, einen Songwriting-Termin ausgemacht.

And then we also arranged a songwriting session right away.

Caption 31, LOTTE & Max Giesinger: Interview

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Ihr könnt doch hier nicht einfach alles ausräumen. So war das nicht ausgemacht.

You can't just clear out everything. This is not what was agreed upon.

Captions 14-15, Lilly unter den Linden: Umzug in die DDR

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A more formal way to agree to something or arrange something would be to use the verb vereinbaren.

Yet a third meaning of ausmachen combines the verb with a dative pronoun (mir, dir, euch, Ihnen, uns). It's often translated as "would you mind," or "if it doesn't disturb you" etc.

Würde es dir was ausmachen, wenn du allein kommst?

Would you mind coming alone?

Caption 71, Meine fremde Freundin: Was alle denken

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Further Learning
Go to the DWDS and Duden definitions linked above and learn a couple of the less-used meanings of ausmachen. Then go to find some more examples on German Yabla to see ausmachen used in a real-world context.