Definition from Wiktionary, the free dictionary
placeholder (plural placeholders)
- Something used or included temporarily or as a substitute for something that is not known or must remain generic; that which holds, denotes or reserves a place for something to come later.
- This is placeholder data, so you’ll want to include the real numbers as soon as you have them.
2013 February 14, Scott Tobias, “Film: Reviews: A Good Day To Die Hard”, The Onion AV Club:
that which holds, denotes or reserves a place for something to come later