placeholder
n. countablen. a temporary name, number, or image used to show where something else will go later. You use it when you are not sure of the final details yet.
n. a temporary value or object used to represent a missing or unknown element in a design or data structure. Often used in software development, graphic design, or publishing to maintain layout integrity during the drafting phase.
I used the word 'NAME' as a placeholder for the customer's actual name.
The designer added a gray square as a placeholder for the final logo until the client provided the high-resolution file.
In the initial stages of the database schema, the developers used a generic identifier as a placeholder to ensure the table structure remained consistent before integrating the actual user data.
From place + holder.