When did the term 'the holocaust' first get applied to the experience of European Jewry that occurred prior to and during WW2?
The answer is that it was used suprisingly early.
The New York Times used the term often.
It even has archived articles using that word for the WW2 experience of Jews as early as from 1936:
"Bold practical measures to save those unfortunate millions from total annihilation are now called for ... Great Britain has it within her power to throw open the gates of Palestine and let in the victimised and persecuted Jews escaping from the European holocaust."
~ NY Times, May 31st, 1936
Julian Meltzer used the word in an article that appeared in the paper on May 23rd, 1943:
“the hundreds and thousands of European Jews still surviving the Nazi holocaust”.
~ NY Times, May 23rd, 1943
https://www.nytimes.com/1943/05/23/arch ... w-for.html
Here is an early usage of the term employing the definitive article, viz. 'the holocaust'.
As yet the H letter hasn't been capitalised. It is from 1942.
And isn't from the New York Times:
“This issue of the JEWISH FRONTIER attempts to give some picture of what is happening to the Jews of Europe ... In our calculations of the holocaust that has overtaken the Jews... [w]e speak... of the victims not of war, but of massacre... The annals of mankind hold no similar record of organised murder.”
~ Jewish Frontier, November 1942, p.3.
In Britain on the 5th December 1942, a journal called the News Chronicle published an editorial that had an uppercase title, “HOLOCAUST”.
It appeared in the second column of the second page.
Hitler has familiarised the world with brutality and terror... But nothing... is comparable to his treatment of the Jews...
...more than half of Poland's three and a half million Jews have already been done to death... Reprisals are out of the question.
~~ 5th December 1942
Here is an early usage of the term from 1960. It was by Francois Mauriac in his introduction to the 1960 publication of Wiesel's plagiarised work ‘Night’:
For him [Eli Wiesel] ... God is dead ... the God of Abraham, of Isaac, of Jacob ... has vanished forevermore ... in the smoke of a human holocaust exacted by Race, the most voracious of all idols."
Elie Wiesel claimed to be the one who popularised the usage of "the holocaust" for the Jewish WW2 experience:
“May I confess to you that I am afraid I am the one who introduced the word into this framework, and I am not proud of it. I cannot use it anymore”.
Wiesel's first use of it to refer the Jewish WW2 experience was in August 1963:
“One finds this ... even in fiction whose theme has nothing to do with the Nazi holocaust. For example, in Fail Safe, the best seller about an atomic accident.”
~~ Elie Wiesel, The New Leader, 5th August 1963, p. 21
During the world-televised Eichmann show-trial, the American, Jewish-owned New York Times was again using the word in its news articles:
Counsel says mercy might help avert new Holocaust
“Eichmann ... might ... serve as an instrument against any recurrence of a Nazi holocaust."
...[The Attorney General of Israel stated]: 'the overwhelming majority of this country [identify] with the victims of the holocaust...”
New York Times, 24 March 1962, p. 7, col. 1.
Here Hanna Arendt and Ben-Gurion used the word in 1963:
And if the Jews outside Israel had to be shown the difference between Israeli heroism and Jewish submissive meekness, there was a complementary lesson for the Israelis; for 'the generation of Israelis who have grown up since the holocaust'..."
~~ Hanna Arendt quoting Ben-Gurion. New Yorker, 16th February 1963, p. 42)
And here the word was used in an essay title on 'Judaism' by Shaul Esh:
The Dignity of the Destroyed: Towards a Definition of the Period of the Holocaust
~ Shaul Esh, 1962, p. 99.)