Eighth letter of the Greek alphabet
Theta
(
,
; uppercase
Θ
or
?
; lowercase
θ
[note 1]
or
?
;
Ancient Greek
:
θ?τα
th??ta
[t???ːta]
;
Modern
:
θ?τα
th??ta
[?θita]
) is the eighth letter of the
Greek alphabet
, derived from the
Phoenician letter
Teth
. In the system of
Greek numerals
, it has a value of 9.
Greek
[
edit
]
The alphabet on a
black figure
vessel, with a point-and-circle theta
In
Ancient Greek
, θ represented the
aspirated
voiceless dental plosive
IPA:
[t??]
, but in
Modern Greek
it represents the
voiceless dental fricative
IPA:
[θ]
.
Forms
[
edit
]
In its
archaic
form, θ was written as a cross within a circle (as in the Etruscan
or
), and later, as a line or point in circle (
or
).
The cursive form ? was retained by
Unicode
as
U+03D1
ϑ
GREEK THETA SYMBOL
, separate from
U+03B8
θ
GREEK SMALL LETTER THETA
. (There is also
U+03F4
ϴ
GREEK CAPITAL THETA SYMBOL
). For the purpose of writing Greek text, the two can be font variants of a single character, but θ and ? are also used as distinct symbols in technical and mathematical contexts. Extensive lists of examples follow below at Mathematics and Science.
U+03D1
ϑ
GREEK THETA SYMBOL
(script theta) is also common in biblical and theological usage e.g. πρ??εσι? instead of πρ?θεσι? (means placing in public or laying out a corpse).
Latin
[
edit
]
The name ARAÐÐOVNA on a Gaulish tombstone
In Latin script used for the
Gaulish language
, theta inspired the
tau gallicum
(
). The phonetic value of the
tau gallicum
is thought to have been
[t?s]
.
[1]
Theta itself is used alongside Latin letters in
Halkomelem
, an
indigenous North American language
.
Cyrillic
[
edit
]
The
early Cyrillic
letter
fita
(?, ?) developed from θ. This letter existed in the
Russian alphabet
until the
1918 Russian orthography reform
.
International Phonetic Alphabet
[
edit
]
In the
International Phonetic Alphabet
(IPA),
[θ]
represents the
voiceless dental fricative
, as in
th
ick
or
th
in
. It does not represent the consonant in
th
e
, which is the
voiced dental fricative
counterpart, represented in the IPA by
[ð]
(cf.
Eth
). A similar-looking lower-case symbol,
[?]
, which is called
barred o
, is the IPA symbol for the
close-mid central rounded vowel
.
Mathematics and science
[
edit
]
Lower case
[
edit
]
The lowercase letter θ is used as a symbol for:
Upper case
[
edit
]
The uppercase letter Θ is used as a symbol for:
Symbolism
[
edit
]
θ (θ?νατο?, death) in a mosaic
In ancient times,
Tau
was used as a symbol for
life
or
resurrection
, whereas the eighth letter of the Greek alphabet (ninth in the archaic form anciently used for numeration), theta, was considered the symbol of
death
.
[3]
A quotation attributed to the ancient Roman author
Ennius
(though possibly spuriously) said of it: "oh, theta, a letter much unluckier than the others".
[4]
According to
Porphyry of Tyros
, the
Egyptians
used an X within a circle as a
symbol
of the soul; having a value of nine, it was used as a symbol for
Ennead
.
Johannes Lydus
says that the
Egyptians
used a symbol for
Kosmos
in the form of theta, with a fiery circle representing the world, and a snake spanning the middle representing
Agathos Daimon
(literally:
good spirit
).
[5]
Abbreviation
[
edit
]
In classical Athens, it was used as an abbreviation for the
Greek
θ?νατο? (
Thanatos
, "death") and as it vaguely resembles a human skull,
[5]
theta was used as a warning symbol of
death
, in the same way that
skull and crossbones
are used in modern times.
[5]
It survives on
potsherds
used by Athenians when voting for the
death penalty
.
[5]
Petrus de Dacia
in a document from 1291 relates the idea that theta was used to brand criminals as empty ciphers, and the branding rod was affixed to the crossbar spanning the circle.
[6]
For this reason, the use of the number 9 was sometimes avoided where the connotation was felt to be unlucky?the mint marks of some Late Imperial Roman coins famously have the sum ΔΕ or ΕΔ (delta and epsilon, that is 4 and 5) substituted as a
euphemism
where a Θ (9) would otherwise be expected.
Character encodings
[
edit
]
Character information
Preview
|
Θ
|
θ
|
ϑ
|
ϴ
|
ᶿ
|
Unicode name
|
GREEK CAPITAL LETTER THETA
|
GREEK SMALL LETTER THETA
|
GREEK THETA SYMBOL
|
GREEK CAPITAL THETA SYMBOL
|
MODIFIER LETTER SMALL THETA
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
Unicode
|
920
|
U+0398
|
952
|
U+03B8
|
977
|
U+03D1
|
1012
|
U+03F4
|
7615
|
U+1DBF
|
UTF-8
|
206 152
|
CE 98
|
206 184
|
CE B8
|
207 145
|
CF 91
|
207 180
|
CF B4
|
225 182 191
|
E1 B6 BF
|
Numeric character reference
|
Θ
|
Θ
|
θ
|
θ
|
ϑ
|
ϑ
|
ϴ
|
ϴ
|
ᶿ
|
ᶿ
|
Named character reference
|
Θ
|
θ
|
ϑ, ϑ, ϑ
|
|
|
DOS Greek
|
135
|
87
|
159
|
9F
|
|
|
|
|
|
|
DOS Greek-2
|
172
|
AC
|
226
|
E2
|
|
|
|
|
|
|
Windows 1253
|
200
|
C8
|
232
|
E8
|
|
|
|
|
|
|
TeX
|
\Theta
|
\theta
|
\vartheta
|
|
|
Character information
Preview
|
Ⲑ
|
ⲑ
|
Unicode name
|
COPTIC CAPITAL LETTER THETHE
|
COPTIC SMALL LETTER THETHE
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
Unicode
|
11408
|
U+2C90
|
11409
|
U+2C91
|
UTF-8
|
226 178 144
|
E2 B2 90
|
226 178 145
|
E2 B2 91
|
Numeric character reference
|
Ⲑ
|
Ⲑ
|
ⲑ
|
ⲑ
|
Character information
Preview
|
Ѳ
|
ѳ
|
Unicode name
|
CYRILLIC CAPITAL LETTER FITA
|
CYRILLIC SMALL LETTER FITA
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
Unicode
|
1138
|
U+0472
|
1139
|
U+0473
|
UTF-8
|
209 178
|
D1 B2
|
209 179
|
D1 B3
|
Numeric character reference
|
Ѳ
|
Ѳ
|
ѳ
|
ѳ
|
Character information
Preview
|
𝚯
|
𝛉
|
𝚹
|
𝛝
|
Unicode name
|
MATHEMATICAL BOLD
CAPITAL THETA
|
MATHEMATICAL BOLD
SMALL THETA
|
MATHEMATICAL BOLD
CAPITAL THETA SYMBOL
|
MATHEMATICAL BOLD
THETA SYMBOL
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
Unicode
|
120495
|
U+1D6AF
|
120521
|
U+1D6C9
|
120505
|
U+1D6B9
|
120541
|
U+1D6DD
|
UTF-8
|
240 157 154 175
|
F0 9D 9A AF
|
240 157 155 137
|
F0 9D 9B 89
|
240 157 154 185
|
F0 9D 9A B9
|
240 157 155 157
|
F0 9D 9B 9D
|
UTF-16
|
55349 57007
|
D835 DEAF
|
55349 57033
|
D835 DEC9
|
55349 57017
|
D835 DEB9
|
55349 57053
|
D835 DEDD
|
Numeric character reference
|
𝚯
|
𝚯
|
𝛉
|
𝛉
|
𝚹
|
𝚹
|
𝛝
|
𝛝
|
Character information
Preview
|
𝛩
|
𝜃
|
𝛳
|
𝜗
|
Unicode name
|
MATHEMATICAL ITALIC
CAPITAL THETA
|
MATHEMATICAL ITALIC
SMALL THETA
|
MATHEMATICAL ITALIC
CAPITAL THETA SYMBOL
|
MATHEMATICAL ITALIC
THETA SYMBOL
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
Unicode
|
120553
|
U+1D6E9
|
120579
|
U+1D703
|
120563
|
U+1D6F3
|
120599
|
U+1D717
|
UTF-8
|
240 157 155 169
|
F0 9D 9B A9
|
240 157 156 131
|
F0 9D 9C 83
|
240 157 155 179
|
F0 9D 9B B3
|
240 157 156 151
|
F0 9D 9C 97
|
UTF-16
|
55349 57065
|
D835 DEE9
|
55349 57091
|
D835 DF03
|
55349 57075
|
D835 DEF3
|
55349 57111
|
D835 DF17
|
Numeric character reference
|
𝛩
|
𝛩
|
𝜃
|
𝜃
|
𝛳
|
𝛳
|
𝜗
|
𝜗
|
Character information
Preview
|
𝜣
|
𝜽
|
𝜭
|
𝝑
|
Unicode name
|
MATHEMATICAL BOLD ITALIC
CAPITAL THETA
|
MATHEMATICAL BOLD ITALIC
SMALL THETA
|
MATHEMATICAL BOLD ITALIC
CAPITAL THETA SYMBOL
|
MATHEMATICAL BOLD ITALIC
CAPITAL THETA SYMBOL
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
Unicode
|
120611
|
U+1D723
|
120637
|
U+1D73D
|
120621
|
U+1D72D
|
120657
|
U+1D751
|
UTF-8
|
240 157 156 163
|
F0 9D 9C A3
|
240 157 156 189
|
F0 9D 9C BD
|
240 157 156 173
|
F0 9D 9C AD
|
240 157 157 145
|
F0 9D 9D 91
|
UTF-16
|
55349 57123
|
D835 DF23
|
55349 57149
|
D835 DF3D
|
55349 57133
|
D835 DF2D
|
55349 57169
|
D835 DF51
|
Numeric character reference
|
𝜣
|
𝜣
|
𝜽
|
𝜽
|
𝜭
|
𝜭
|
𝝑
|
𝝑
|
Character information
Preview
|
𝝝
|
𝝷
|
𝚹
|
𝞋
|
Unicode name
|
MATHEMATICAL SANS-SERIF
BOLD CAPITAL THETA
|
MATHEMATICAL SANS-SERIF
BOLD SMALL THETA
|
MATHEMATICAL SANS-SERIF
BOLD CAPITAL THETA SYMBOL
|
MATHEMATICAL SANS-SERIF
BOLD THETA SYMBOL
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
Unicode
|
120669
|
U+1D75D
|
120695
|
U+1D777
|
120505
|
U+1D6B9
|
120715
|
U+1D78B
|
UTF-8
|
240 157 157 157
|
F0 9D 9D 9D
|
240 157 157 183
|
F0 9D 9D B7
|
240 157 154 185
|
F0 9D 9A B9
|
240 157 158 139
|
F0 9D 9E 8B
|
UTF-16
|
55349 57181
|
D835 DF5D
|
55349 57207
|
D835 DF77
|
55349 57017
|
D835 DEB9
|
55349 57227
|
D835 DF8B
|
Numeric character reference
|
𝝝
|
𝝝
|
𝝷
|
𝝷
|
𝚹
|
𝚹
|
𝞋
|
𝞋
|
Character information
Preview
|
𝞗
|
𝞱
|
𝜭
|
𝟅
|
Unicode name
|
MATHEMATICAL SANS-SERIF
BOLD ITALIC CAPITAL THETA
|
MATHEMATICAL SANS-SERIF
BOLD ITALIC SMALL THETA
|
MATHEMATICAL SANS-SERIF
BOLD ITALIC CAPITAL THETA SYMBOL
|
MATHEMATICAL SANS-SERIF
BOLD ITALIC THETA SYMBOL
|
Encodings
|
decimal
|
hex
|
dec
|
hex
|
dec
|
hex
|
dec
|
hex
|
Unicode
|
120727
|
U+1D797
|
120753
|
U+1D7B1
|
120621
|
U+1D72D
|
120773
|
U+1D7C5
|
UTF-8
|
240 157 158 151
|
F0 9D 9E 97
|
240 157 158 177
|
F0 9D 9E B1
|
240 157 156 173
|
F0 9D 9C AD
|
240 157 159 133
|
F0 9D 9F 85
|
UTF-16
|
55349 57239
|
D835 DF97
|
55349 57265
|
D835 DFB1
|
55349 57133
|
D835 DF2D
|
55349 57285
|
D835 DFC5
|
Numeric character reference
|
𝞗
|
𝞗
|
𝞱
|
𝞱
|
𝜭
|
𝜭
|
𝟅
|
𝟅
|
These characters are used only as mathematical symbols. Stylized Greek text should be encoded using normal Greek letters, with markup and formatting to indicate text style.
See also
[
edit
]
Look up
Θ
or
θ
in Wiktionary, the free dictionary.
Notes and references
[
edit
]
Notes
[
edit
]
- ^
which resembles digit
0
with a horizontal line.
References
[
edit
]
- ^
Everson, Michael; Lilley, Chris (2019-05-26).
"L2/19-179: Proposal for the addition of four Latin characters for Gaulish"
(PDF)
.
- ^
Feferman, Solomon (2010). Schindler, Ralf (ed.).
"The Proof Theory of Classical and Constructive Inductive Definitions. A Forty Year Saga, 1968 ? 2008"
(PDF)
.
Ways of Proof Theory
: 7?30.
- ^
Mednikarova, Iveta (2001). "The Use of Θ in Latin Funerary Inscriptions".
Zeitschrift fur Papyrologie und Epigraphik
.
136
: 267?276.
JSTOR
20190914
.
- ^
Ennius, Quintus
(2018). Goldberg, Sander M.;
Manuwald, Gesine
(eds.).
Fragmentary Republican Latin, Volume I: Ennius, Testimonia. Epic Fragments
. Cambridge, MA: Harvard University Press. pp. 456?457.
- ^
a
b
c
d
Barry, Kieren (1998),
The Greek Qabalah: Alphabetic Mysticism and Numerology in the Ancient World
,
Samuel Weiser
, p. 73,
ISBN
1-57863-110-6
.
- ^
Kaplan, Robert (2000),
The Nothing that Is: A Natural History of Zero
, Oxford; New York:
Oxford University Press
, p. 66,
Bibcode
:
2000tnti.book.....K
,
ISBN
0-19-514237-3
.