Ersatz means “substituting for, and typically inferior in quality to”, e.g. “chicory is ersatz coffee”. It is a German word literally meaning substitute or replacement
The term ersatz gained international attention during World War I for at least two reasons. In the opening months of the war, replacement troops for battle-depleted German infantry units were drawn from lesser-trained Ersatz Corps. Unsurprisingly, these under-prepared soldiers were considered less effective than the troops they replaced. Also, the Allied naval blockade of Germany throttled maritime commerce with Germany, forcing Germany to develop substitutes for products like chemical compounds and provisions. Ersatz products developed during this time included: synthetic rubber (produced from oil), benzene for heating oil (coal gas), tea composed of ground raspberry leaves or catnip, and coffee, using roasted acorns or beans instead of coffee beans. Though a similar situation arose in Germany during World War II, this connotation with the term ersatz has fallen into disuse in Germany.