E.g. entering the kitchen, preparing food, and leaving a mess; or entering the kitchen, preparing food, and leaving everything as it was before.

How do you call this concept? "I take some actions, but after I am done, everything is the same". This also applies that you can repeat the exact same action.

EDIT: I feel this concept in my current living situation. For the week I live in an Airbnb apartment in a different city, and when I come home on the weekend, I could get a dismissal any day and I would not have to "clean up after myself", as opposed when I had a rented flat in the city.


2 Answers 2


In mathematics or computer science, the most common term for this property is idempotence, and an action (or mathematical transformation, or computer program) is said to be idempotent.

Technically, the term means "the ability to be performed repeatedly without changing anything".

I've not heard the word used outside of those contexts except as a joke.

  • I feel like idempotence is different because there is an initial change. E.g. setNumberTo5(x) is idempotent, but there is an initial change. I just means you can apply it multiple times without any further change.
    – hgiesel
    Mar 10, 2017 at 9:49
  • That's a good point, especially with regards to math. In computer science, though, the term generally means "causes no change", even on the first try. For example, in software design, a good unit test is always idempotent - after running, it leaves the system in the same state it had prior to running the test. Mar 10, 2017 at 9:58
  • "left (or finished or exited) without leaving a trace."
    – Xanne
    Mar 10, 2017 at 10:20

A functional term I have come across, which describes this notion is:

"without side effect"

The world is the same when you started the action, as it was before. Of course that's not really the case, but it feels like it.

EDIT: Another phrase I've come across, and which describes this situation is "with a clean slate". E.g. "Every week I start with a clean slate."

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