Ersatz
Etymology
From German Ersatz (“substitute, replacement”), a noun from ersetzen (“to replace”). It entered English around the First World War, when blockaded Germany relied on ersatz goods — coffee from roasted grain, rubber from chemicals — and the word carried that sense of a poor but frank imitation.
adjective · /ER-zahts/
Being an inferior substitute for the real thing, and not pretending otherwise.
What it names
The honest stand-in — the make-do replacement that everyone knows is a lesser version of what it stands in for.
Example
The diner served an ersatz cream sauce that was mostly cornstarch and hope.
Related idea
A counterfeit pretends to be the real thing; something ersatz openly admits it is only a substitute.