noun

DMG

dee-em-JEE

DMG (noun) means a macOS file that behaves like a disk: opening one makes its contents appear as a mounted drive on the desktop, from which software is usually installed by dragging the application into the Applications folder. Such files normally end in .dmg. Example: “Open the DMG and drag the app icon across to Applications.”

noun

technical, computing A macOS file that behaves like a disk: opening one makes its contents appear as a mounted drive on the desktop, from which software is usually installed by dragging the application into the Applications folder. Such files normally end in .dmg.

"Open the DMG and drag the app icon across to Applications."

"The download is a 240 MB DMG."

How to Use DMG

Learner’s notes

In plain EnglishA Mac file that opens like a pretend disk, usually so you can install a program from it.

When to use it

Technical, specific to Apple systems. Written in capitals, or lower case as the extension .dmg.

Memory tip

Spelled out letter by letter; it is never pronounced as a word.

Trace the full origin ↓

Easily confused with

ISO → PKG EXE → MSI ZIP →

Common pairings

DMG file mount a DMG open the .dmg eject the disk image

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Fill the Gap

Can you complete this real example?

Open the _____ and drag the app icon across to Applications.

Etymology

A shortening of disk image.

Origin: English

Synonyms

View more →

disk image Apple Disk Image mountable image installer image

Frequently Asked Questions

How do I install something from a DMG?

Double-clicking the DMG mounts it, which puts a temporary drive icon on the desktop and in Finder's sidebar. Most DMGs then show a window with the application and a shortcut to the Applications folder; dragging the app across copies it to your Mac. Afterwards the mounted image can be ejected and the DMG file deleted.

What is the difference between a DMG and an EXE?

A DMG is a container, not a program: it holds files and presents them as a disk on macOS. An EXE is an actual executable that Windows runs. The closest Windows equivalents to a DMG are an MSI installer or a ZIP file, depending on what the DMG contains.

Can DMG files hold anything besides apps?

Yes. A disk image can contain any files at all, and can be encrypted or made read-only, so DMGs are also used to bundle documents, back up a folder, or hand over a set of files as a single sealed package.