|Look up ersatz in Wiktionary, the free dictionary.|
Ersatz (German pronunciation: [ɛrˈzats]) 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. Although it is used as an adjective in English, Ersatz can only function in German as a noun on its own, or as a part in compound nouns such as Ersatzteile (spare parts) or Ersatzspieler (substitute player). While the term used in English often implies that the substitution is of unsatisfactory or inferior quality compared to the "real thing," it has both connotations in German, depending on the other noun; e.g. 'Ersatzteile' (spare parts) is a technical expression without any implication about quality, whereas in other cases it may mean things of poorer quality, e.g. 'Ersatzkaffee' ("coffee" not made from coffee beans). Another German word for "Ersatz-" is Surrogat (surrogate).
In English, "ersatz" arose as a pejorative during World War II because Ersatzbrot (replacement bread) made of potato starch, frequently stretched with extenders such as sawdust, was often given to prisoners of war. This practice was prevalent on the Eastern front and at the many Nazi labour and death camps.
In Britain, this was additionally popularised as an adjective, from the experiences of thousands of U.S., British, and other English-speaking combat personnel, primarily airmen, who were captured in the European Theater of Operations during World War II. These Allied Kriegsgefangene (prisoners of war) were given Ersatzkaffee (an inferior Getreidekaffee or "grain coffee") as a coffee substitute by their German captors.
The reason for Ersatz being only a noun in German but also an adjective in English is that in German compound nouns are single words formed by concatenating the constituent nouns, while in English the constituents tend to remain separate words. In the case of Ersatzkaffee, in which the latter two syllables were recognisably "coffee" to English-speaking ears, this compound noun was anglicised by a calque translation that retained the constituent Ersatz as a loanword, resulting in "ersatz coffee", in which the first part was interpreted as an adjective. In this way, "ersatz" came to be an English adjective connoting an inferior substitute.
Historical context 
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, who were 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 such as chemical compounds and provisions. Ersatz products developed during this time included: synthetic rubber (produced from petroleum), benzene for heating oil (coal gas), tea composed of ground raspberry leaves or catnip, and coffee substitute 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.
Another example of the word's usage in Germany exists in the German naval construction programs of the beginning of the 20th century. In this context, the phrasing "Ersatz (shipname)" indicates that a new, larger, or more capable ship was a replacement for an aging or lost previous vessel. Because German practice was not to reveal the name of a new ship until its launch, this meant that the vessel was known by its "Ersatz (shipname)" throughout its construction. At the end of World War I, the last three ships of the planned Mackensen class of battlecruisers were redesigned and initially known simply as the Ersatz Yorck class, since the first ship was considered to be a replacement for the lost armored cruiser Yorck.