What is the difference between "coalesce" and "merge"?

In my native language, I get a similar translation of these words.

For example:

I coalesce the code

I merge the code

  • 1
    Note that “merge” and “coalesce” have specific technical meanings in programming that are not interchangeable. And this use of “coalesce” is transitive, whereas the word is only intransitive in general English.
    – StephenS
    Commented Oct 24, 2020 at 17:20

3 Answers 3


They have similar meanings.

"Merge" is a more common word. For code, merge is the only idiomatic option. Likewise for traffic, corporations, and many other subjects.

"Coalesce" is a less common word that may apply to natural processes such as water droplets, lakes, abstract concepts such as theories, and others.


One difference is that coalesce is an intransitive verb - it cannot take a direct object as it does in your sentence. Merge can be transitive so it can be used as in your sentence.

In terms of meaning, the words are very similar and are probably interchangeable in some contexts. Having said that, my feeling is that coalesce sounds more natural with abstract nouns:

The two roads merged into one. (natural)
The two roads coalesced into one. (unnatural?)

This painting shows how two styles merged into one. (natural)
This painting shows how two styles coalesced into one. (natural)


If you ask me, "merge" tends to be the joining of TWO bodies. The implication of two is there, whereas coalesce can be two or also multiple things coming together

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