Military. The day on which a military operation is scheduled to begin. Also in extended use: the day on which any significant event or activity is scheduled to begin or take place. Cf. zero hourn. 1.
1917
The assault, which will be preceded by a five days' artillery bombardment, will take place about dawn on Zero day.
Attack Brit. 9th Corps Messines Ridge (U.S. War Dept. Doc. No. 653) 12
1947
I..fixed a zero-day three months ahead.
L. Hastings, Dragons are Extra iv. 80
1952
Stilfontein's zero day is Tuesday next, when the mine will officially be producing gold.
Financial Times 30 June 3/2
1978
20th October had been fixed as Zero Day for rocket attacks on London to begin.
R. V. Jones, Most Secret War xxxix. 350
2007
Working parties had filled in shell craters and bridged trenches in order to have roads built as far as the front line by zero day.
P. D. Dickson, Thoroughly Canadian General iii. 53
attributive. Designating (an item of) commercial software, media, etc., illegally made available via the internet on the same day as (or sometimes earlier than) its official release. Chiefly in zero day warez (see warezn.).
[1992
The target for all these groups was ‘zero wares’, software that had been cracked less than 24 hours earlier—zero days.
Sydney Morning Herald (Nexis) 28 September 18]
1993
There was talk in this group about zero day warez.
Goal! Piracy in comp.sys.amiga.advocacy 28 June (Usenet newsgroup, accessed 11 Jan. 2018)
2004
Zero Day cracks appear even before the products have been released.
What Crap is This? in comp.os.linux.advocacy (Usenet newsgroup, accessed 11 Jan. 2018) 24 July
2017
Oh that kind of pirate. I was going to bring up BitTorrent and zero day warez.
@MCWronski 19 September in twitter.com (accessed 11 Jan. 2018)
attributive. Designating a software vulnerability that is unknown to the developer or vendor, making it vulnerable to an attack until it is discovered and fixed; designating an attack or method of attack which exploits such a vulnerability.
2000
The so-called zero day exploit list..features a minimum of 100 fresh vulnerabilities a week.
‘We're the Good Guys’ claim Hackers in alt.hit2000.nl 14 April (Usenet newsgroup, accessed 11 Jan. 2018)
2006
The attacks..use phishing e-mails to get employees to open e-mail attachments or visit Web sites that download Trojans targeting ‘zero-day’ vulnerabilities in common apps.
InfoWorld 30 October 26/1
2017
The breach could be the result of a so-called zero-day attack, one that exploits a flaw in software not identified or patched by the supplier.
Some consonants can take the function of the vowel in unstressed syllables. Where necessary, a syllabic marker diacritic is used, hence /ˈpɛtl/ but /ˈpɛtl̩i/.
Vowels
iːfleece
ihappy
ɪkit
ɛdress
atrap, bath
ɑːstart, palm, bath
ɒlot
ɔːthought, force
ʌstrut
ʊfoot
uːgoose
əletter
əːnurse
ɪənear
ɛːsquare
ʊəcure
eɪface
ʌɪpride
aʊmouth
əʊgoat
ɔɪvoice
ãgratin
ɒ̃salon
ᵻ(/ɪ/-/ə/)
ᵿ(/ʊ/-/ə/)
Other symbols
The symbol ˈ at the beginning of a syllable indicates that that syllable is pronounced with primary stress.
The symbol ˌ at the beginning of a syllable indicates that that syllable is pronounced with secondary stress.
Round brackets ( ) in a transcription indicate that the symbol within the brackets is optional.
Some consonants can take the function of the vowel in unstressed syllables. Where necessary, a syllabic marker diacritic is used, hence /ˈpɛd(ə)l/ but /ˈpɛdl̩i/.
Vowels
ifleece, happy
ɪkit
ɛdress
ætrap, bath
ɑlot, palm, cloth, thought
ɑrstart
ɔcloth, thought
ɔrnorth, force
ʊfoot
ugoose
əstrut, comma
ərnurse, letter
ɪ(ə)rnear
ɛ(ə)rsquare
ʊ(ə)rcure
eɪface
aɪpride
aʊmouth
oʊgoat
ɔɪvoice
ɑ̃gratin
æ̃salon
ᵻ(/ɪ/-/ə/)
ᵿ(/ʊ/-/ə/)
Other symbols
The symbol ˈ at the beginning of a syllable indicates that that syllable is pronounced with primary stress.
The symbol ˌ at the beginning of a syllable indicates that that syllable is pronounced with secondary stress.
Round brackets ( ) in a transcription indicate that the symbol within the brackets is optional.
Simple text respell breaks words into syllables, separated by a hyphen. The syllable which carries the primary stress is written in capital letters. This key covers both British and U.S. English Simple Text Respell.
Consonants
b, d, f, h, k, l, m, n, p, r, s, t, v, w and z have their standard English values
zero day typically occurs about 0.02 times per million words in modern written English.
zero day is in frequency band 3, which contains words occurring between 0.01 and 0.1 times per million words in modern written English. More about OED's frequency bands
Frequency data is computed programmatically, and should be regarded as an estimate.
Frequency of zero day, n., 1910–2010
* Occurrences per million words in written English
Historical frequency series are derived from Google Books Ngrams (version 2), a data set based on the Google Books corpus of several million books printed in English between 1500 and 2010.
The overall frequency for a given word is calculated by summing frequencies for the main form of the word, any plural or inflected forms, and any major spelling variations.
For sets of homographs (distinct entries that share the same word-form, e.g. mole, n.¹, mole, n.², mole, n.³, etc.), we have estimated the frequency of each homograph entry as a fraction of the total Ngrams frequency for the word-form. This may result in inaccuracies.
Smoothing has been applied to series for lower-frequency words, using a moving-average algorithm. This reduces short-term fluctuations, which may be produced by variability in the content of the Google Books corpus.
Decade
Frequency per million words
1910
0.023
1920
0.024
1930
0.024
1940
0.023
1950
0.023
1960
0.021
1970
0.021
1980
0.02
1990
0.019
2000
0.018
2010
0.018
Frequency of zero day, n., 2017–2024
* Occurrences per million words in written English
Modern frequency series are derived from a corpus of 20 billion words, covering the period from 2017 to the present. The corpus is mainly compiled from online news sources, and covers all major varieties of World English.
Smoothing has been applied to series for lower-frequency words, using a moving-average algorithm. This reduces short-term fluctuations, which may be produced by variability in the content of the corpus.
Period
Frequency per million words
2017
0.33
2018
0.36
2019
0.45
2020
0.53
2021
0.58
2022
0.58
2023
0.62
2024
0.55
Originally published as part of the entry for zero, n. & adj.