Learn Spanish (Latin America): Se me descosió el cierre del abrigo nuevo. - The zipper of my new coat came unstitched.

Using se + indirect object (me) + verb is the standard way to talk about accidents in Spanish. Saying rompí mi cierre sounds like you ruined it on purpose! Saying mi cierre se descosió is okay, but adding the me (the accidental se structure) emphasizes that this unexpected, involuntary event happened to you and affected you.

Why is the verb in the third-person singular (descosió) if this happened to me?

In the accidental se construction, the person affected is just the indirect object (me). The actual grammatical subject of the sentence is the thing that broke or failed. Since el cierre (the zipper) is doing the action of coming unstitched, the verb agrees with it, giving us the third-person singular descosió.

I usually see cremallera for "zipper." Is cierre more common?

Yes, in Latin America, cierre is the standard, everyday word for a zipper, whereas cremallera is primarily used in Spain. Because cierre comes from the verb cerrar (to close), you can easily remember it as "the closer."

Is descosió related to the verb coser?