In
geometry
Geometry (; ) is, with arithmetic, one of the oldest branches of mathematics. It is concerned with properties of space such as the distance, shape, size, and relative position of figures. A mathematician who works in the field of geometry is c ...
, an enneagram (🟙 U+1F7D9) is a nine-pointed plane figure. It is sometimes called a nonagram, nonangle, or enneagon.
The word 'enneagram' combines the
numeral prefix
Numeral or number prefixes are prefixes derived from Numeral (linguistics), numerals or occasionally other numbers. In English and many other languages, they are used to coin numerous series of words. For example:
* unicycle, bicycle, tricycle (1 ...
''
ennea-
Numeral or number prefixes are prefixes derived from numerals or occasionally other numbers. In English and many other languages, they are used to coin numerous series of words. For example:
* unicycle, bicycle, tricycle (1-cycle, 2-cycle, 3-cyc ...
'' with the
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
suffix ''
-gram''. The ''gram'' suffix derives from ''γραμμῆς'' (''grammēs'') meaning a line.
Regular enneagram
A regular enneagram is a 9-sided
star polygon
In geometry, a star polygon is a type of non-convex polygon. Regular star polygons have been studied in depth; while star polygons in general appear not to have been formally defined, certain notable ones can arise through truncation operations ...
. It is constructed using the same points as the regular
enneagon
In geometry, a nonagon () or enneagon () is a nine-sided polygon or 9-gon.
The name ''nonagon'' is a prefix hybrid formation, from Latin (''nonus'', "ninth" + ''gonon''), used equivalently, attested already in the 16th century in French ''nonogo ...
, but the points are connected in fixed steps. Two forms of regular enneagram exist:
*One form connects every second point and is represented by the
Schläfli symbol
In geometry, the Schläfli symbol is a notation of the form \ that defines regular polytopes and tessellations.
The Schläfli symbol is named after the 19th-century Swiss mathematician Ludwig Schläfli, who generalized Euclidean geometry to more ...
.
*The other form connects every fourth point and is represented by the Schläfli symbol .
There is also a star figure, or 3, made from the regular enneagon points but connected as a compound of three equilateral triangles. (If the triangles are alternately interlaced, this results in a
Brunnian link
In knot theory, a branch of topology, a Brunnian link is a nontrivial link that becomes a set of trivial unlinked circles if any one component is removed. In other words, cutting any loop frees all the other loops (so that no two loops can be ...
.) This star figure is sometimes known as the ''star of
Goliath
Goliath ( ) ''Goləyāṯ''; ar, جُليات ''Ǧulyāt'' (Christian term) or (Quranic term). is a character in the Book of Samuel, described as a Philistine giant
In folklore, giants (from Ancient Greek: ''gigas'', cognate giga-) a ...
'', after
or 2, the star of
David
David (; , "beloved one") (traditional spelling), , ''Dāwūd''; grc-koi, Δαυΐδ, Dauíd; la, Davidus, David; gez , ዳዊት, ''Dawit''; xcl, Դաւիթ, ''Dawitʿ''; cu, Давíдъ, ''Davidŭ''; possibly meaning "beloved one". w ...
.
Other enneagram figures
The nine-pointed star or enneagram can also symbolize the nine gifts or
fruits of the Holy Spirit
The Fruit of the Holy Spirit (sometimes, incorrectly, referred to as the Fruits of the Holy Spirit) is a biblical term that sums up nine attributes of a person or community living in accord with the Holy Spirit, according to chapter 5 of the Epi ...
.
In popular culture
*The
heavy metal band
Slipknot previously used the star figure enneagram
and currently uses the polygon as a symbol. The prior figure can be seen on the cover of
All Hope Is Gone
''All Hope Is Gone'' is the fourth studio album by American heavy metal band Slipknot, released on August 26, 2008 by Roadrunner Records. The album was published in two versions: the standard album in a CD case and a special edition packaged ...
.
See also
*
List of regular star polygons
*
Baháʼí symbols
There are several symbols used to express identification with the Baháʼí Faith: the nine-pointed star, a calligraphy known as the "Greatest Name", the Ringstone Symbol, or a five-pointed star.
Nine-pointed star
According to the Abjad system ...
References
Bibliography
*
John H. Conway
John Horton Conway (26 December 1937 – 11 April 2020) was an English people, English mathematician active in the theory of finite groups, knot theory, number theory, combinatorial game theory and coding theory. He also made contributions to ...
, Heidi Burgiel, Chaim Goodman-Strass, ''The Symmetries of Things'' 2008, (Chapter 26. pp. 404: Regular star-polytopes Dimension 2)
External links
*
Nonagram -- from Wolfram MathWorld
{{Polygons
9 (number)
09