There are three meanings listed in OED's entry for the word zetetic, one of which is labelled obsolete. See ‘Meaning & use’ for definitions, usage, and quotation evidence.
zetetic has developed meanings and uses in subjects including
<post-classical Latinzeteticus (1591 in a work title: Zeteticorum libri quinque by François Viète) <ancient Greekζητητικός disposed to search or inquire <ζητητής seeker, inquirer (<ζητεῖν to seek…
<post-classical Latinzeteticus (1591 in a work title: Zeteticorum libri quinque by François Viète) <ancient Greekζητητικός disposed to search or inquire <ζητητής seeker, inquirer (<ζητεῖν to seek, inquire (see zealn.) + ‑τής, suffix forming agent nouns) + ‑ικός‑icsuffix.Compare slightly later zeteticaladj.
Notes
Specific senses
With use as noun compare Hellenistic Greekοἱ ζητητικοί (plural), name given to the Sceptics, and ἡ ζητητική (feminine) Sceptic philosophy.
With sense B.1 compare Frenchzététique, masculine noun (1630 in a translation of Viète's work). Compare also the following slightly earlier example of post-classical Latinzetetici, plural, in an English context:
1657
Many others by reason of this professed ignorance, were called..Sceptici, Ephetici, Zetetici and Aporetici, i. e. Considerers, unresolved Seekers, Doubters.
E. Porter, Trin-unus-deus ii. 11
In sense B.2 perhaps after Frenchzététique (1691 in the passage translated in quot. 1702).
Meaning & use
adjective
1645–
Inquiring, investigating; proceeding by inquiry or investigation.
zetetic astronomynoun (after the title of Rowbotham's pamphlet on the subject: see quot. 1849) the theory that the earth is a flat disc, and that the sun, moon, and stars are in motion a short distance above it; hence zetetic astronomer.
1645
Zetetick, is said of Loxogonosphericall Moods which agree in the same quæsitas.
T. Urquhart, Trissotetras sig. Pv
1660
This was called the Zetetick Philosophy, from its continuall enquiry after truth.
T. Stanley, History of Philosophyvol. III.iv. 1
1704
Zetetick Method in Mathematicks, is the Analytick, or Algebraick way.
J. Harris, Lexicon Technicumvol. I
1799
When shall the ingannations of prejudice be delacerated, and the catachrestical reasonings of facinorous aristocrats be dispanded by the zetetic spirit of the eighteenth century?
G. Walker, Vagabondvol. II. ii. 37
1849
Zetetic Astronomy. A description of several experiments which prove that the surface of the sea is a perfect plane and that the Earth is not a Globe!
S. B. Rowbotham(title)
1885
A party of Zetetic astronomers with scientific instruments.
Bookseller 7 January 12/1
1939
A well-known actress.., when asked by a zetetic reporter what was her favorite superstition, replied, ‘Thank Heaven, I have none!’—and unconsciously ‘knocked wood’ as she spoke.
J. Trachtenberg, Jewish Magic & Superstition xi. 153
1971
This paper is zetetic rather than expository.
A. L. Peck in Ess. Ancient Greek Philosophyiii. 478
2001
Aristotle seeks to cultivate in his students a zetetic, critical stance toward their own regime.
An investigator, an inquirer; spec. (frequently capitalized) an adherent of the ancient Greek sceptic school of philosophy (see scepticadj., scepticn. A.1).
1658
In the latter you shew your self to me a Cordiall friend, in the other an ingenious and discreet Zetetick.
G. Starkey, Pyrotechny 159
1660
These all were called Pyrrhonians from their Master; Aporeticks, and Scepticks, and Ephecticks, and Zeteticks, from their (as it were) Doctrine.
T. Stanley, History of Philosophyvol. III.iv. 3
1670
They [sc. the Scepticks] were stiled ζητητικοί, Zeteticks, because they were ever seeking, but never found the truth.
T. Gale, Court of Gentiles: Part IIiv. iv. 435
1751
Or of what was the Use of Searching, expressed by their [sc. the sceptics'] other Name Zetetics, where avowedly nothing was to be found.
London Daily Advertiser & Literary Gazette 27 July
1838
The ancient Pyrrhonists were called Zetetics or seekers.
J. Rowbotham, Dictionary 66
1895
They were known as Sceptics and Zetetics, to indicate that they were always in search of truth without flattering themselves that they had found it.
Med. Age 10 January 6/2
1914
The Zetetics were a school of philosophers who were so called because they professed to be ‘seekers after the truth’.
D. J. Burrell, We would see Jesus vii. 46
2003
I am a zetetic, an agnostic who will try to find out.
An investigator, an inquirer; spec. (frequently capitalized) an adherent of the ancient Greek sceptic school of philosophy (see sceptic, adj., sceptic…
† Originally, with reference to the work of French mathematician François Viète (1540–1603): a method of solving mathematical problems by expressing them in the form of equations and solving these algebraically, according to certain laws (cf. zeteticsn.). In later use more generally: the systematic analysis of problems. Obsolete. rare.
In quot. 1692 perhaps: the system of letters used by Viète in his method to denote constants and variables.
1692
Zetetique, numbers used in Algebra and Equations by the famous Vieta.
H. Coley, Moxon's Mathematicks made Easie (ed. 2) 181
1702
Zetetick[French Zetetique], is a Method made use of to solve Mathematical Problems.
translation of J. Ozanam, Math. Dictionary
1853
[Logic] has been called..Zetetic or the Art of seeking.
W. Thomson, Outline of Laws of Thought (ed. 3) §35
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
gguy
jjay
yyore
chchore
khloch
shshore
ththaw
dhthee
zhbeige
Vowels
atrap
ahpalm
airsquare
arstart
arrcarry (British only)
awthought
ayface
a(ng)gratin
edress
eefleece
eerdeer
errmerry
ikit
ighpride
irrmirror
olot (British only)
ohgoat
oogoose
oorcure
orforce
orrsorry (British only)
owmouth
oyvoice
o(ng)salon
ustrut
uhletter
urnurse
urrhurry
uufoot
Forms
Variant forms
1600s
zetetique
1600s–1700s
zetetick
1700s–
zetetic
Frequency
zetetic typically occurs fewer than 0.01 times per million words in modern written English.
zetetic is in frequency band 2, which contains words occurring between 0.001 and 0.01 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 zetetic, adj. & n., 1790–2010
* 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.