List of polygons explained

In geometry, a polygon is traditionally a plane figure that is bounded by a finite chain of straight line segments closing in a loop to form a closed chain. These segments are called its edges or sides, and the points where two of the edges meet are the polygon's vertices (singular: vertex) or corners.

The word polygon comes from Late Latin polygōnum (a noun), from Greek πολύγωνον (polygōnon/polugōnon), noun use of neuter of πολύγωνος (polygōnos/polugōnos, the masculine adjective), meaning "many-angled". Individual polygons are named (and sometimes classified) according to the number of sides, combining a Greek-derived numerical prefix with the suffix -gon, e.g. pentagon, dodecagon. The triangle, quadrilateral and nonagon are exceptions, although the regular forms trigon, tetragon, and enneagon are sometimes encountered as well.

Greek numbers

Polygons are primarily named by prefixes from Ancient Greek numbers.


English ordinal number	Greek cardinal number	Greek ordinal number
one	first	heis (fem. mia, neut. hen)	protos
two	second	duo	deuteros
three	third	treis	tritos
four	fourth	tettares	tetartos
five	fifth	pente	pemptos
six	sixth	hex	hektos
seven	seventh	hepta	hebdomos
eight	eighth	okto	ogdoös
nine	ninth	ennea	enatos
ten	tenth	deka	dekatos
eleven	eleventh	hendeka	hendekatos
twelve	twelfth	dodeka	dodekatos
thirteen	thirteenth	triskaideka	dekatotritos
fourteen	fourteenth	tettareskaideka	dekatotetartos
fifteen	fifteenth	pentekaideka	dekatopemptos
sixteen	sixteenth	hekkaideka	dekatohektos
seventeen	seventeenth	heptakaideka	dekatohebdomos
eighteen	eighteenth	oktokaideka	dekatoögdoös
nineteen	nineteenth	enneakaideka	dekatoënatos
twenty	twentieth	eikosi	eikostos
twenty-one	twenty-first	heiskaieikosi	eikostoprotos
twenty-two	twenty-second	duokaieikosi	eikostodeuteros
twenty-three	twenty-third	triskaieikosi	eikostotritos
twenty-four	twenty-fourth	tetterakaieikosi	eikostotetartos
twenty-five	twenty-fifth	pentekaieikosi	eikostopemptos
twenty-six	twenty-sixth	hekkaieikosi	eikostohektos
twenty-seven	twenty-seventh	heptakaieikosi	eikostohebdomos
twenty-eight	twenty-eighth	oktokaieikosi	eikostoögdoös
twenty-nine	twenty-ninth	enneakaieikosi	eikostoënatos
thirty	thirtieth	triakonta	triakostos
thirty-one	thirty-first	heiskaitriakonta	triakostoprotos
forty	fortieth	tessarakonta	tessarakostos
fifty	fiftieth	pentekonta	pentekostos
sixty	sixtieth	hexekonta	hexekostos
seventy	seventieth	hebdomekonta	hebdomekostos
eighty	eightieth	ogdoëkonta	ogdoëkostos
ninety	ninetieth	enenekonta	enenekostos
hundred	hundredth	hekaton	hekatostos
hundred and ten	hundred and tenth	dekakaihekaton	hekatostodekatos
hundred and twenty	hundred and twentieth	ikosikaihekaton	hekatostoikostos
two hundred	two hundredth	diakosioi	diakosiostos
three hundred	three hundredth	triakosioi	triakosiostos
four hundred	four hundredth	tetrakosioi	tetrakosiostos
five hundred	five hundredth	pentakosioi	pentakosiostos
six hundred	six hundredth	hexakosioi	hexakosiostos
seven hundred	seven hundredth	heptakosioi	heptakosiostos
eight hundred	eight hundredth	oktakosioi	oktakosiostos
nine hundred	nine hundredth	enneakosioi	enneakosiostos
thousand	thousandth	chilioi	chiliostos
two thousand	two thousandth	dischilioi	dischiliostos
three thousand	three thousandth	trischilioi	trischiliostos
four thousand	four thousandth	tetrakischilioi	tetrakischiliostos
five thousand	five thousandth	pentakischilioi	pentakischiliostos
six thousand	six thousandth	hexakischilioi	hexakischiliostos
seven thousand	seven thousandth	heptakischilioi	heptakischiliostos
eight thousand	eight thousandth	oktakischilioi	oktakischiliostos
nine thousand	nine thousandth	enneakischilioi	enneakischiliostos
ten thousand	ten thousandth	myrioi	myriastos
twenty thousand	twenty thousandth	dismyrioi	dismyriastos
thirty thousand	thirty thousandth	trismyrioi	trismyriastos
forty thousand	forty thousandth	tetrakismyrioi	tetrakismyriastos
fifty thousand	fifty thousandth	pentakismyrioi	pentakismyriastos
sixty thousand	sixty thousandth	hexakismyrioi	hexakismyriastos
seventy thousand	seventy thousandth	heptakismyrioi	heptakismyriastos
eighty thousand	eighty thousandth	oktakismyrioi	oktakismyriastos
ninety thousand	ninety thousandth	enneakismyrioi	enneakismyriastos
hundred thousand	hundred thousandth	dekakismyrioi	dekakismyriastos
two hundred thousand	two hundred thousandth	ikosakismyrioi	ikosakismyriastos
three hundred thousand	three hundred thousandth	triakontakismyrioi	triakontakismyriastos
million	millionth	hekatontakismyrioi	hekatontakismyriastos
two million	two millionth	diakosakismyrioi	diakosakismyriastos
three million	three millionth	triakosakismyrioi	triakosakismyriastos
ten million	ten millionth	chiliakismyrioi	chiliakismyriastos
hundred million	hundred millionth	myriakismyrioi	myriakismyriastos

Systematic polygon names

To construct the name of a polygon with more than 20 and fewer than 100 edges, combine the prefixes as follows. The "kai" connector is not included by some authors.

Tens		and	Ones		final suffix
Tens		-kai-	1		-hena-	-gon
20	icosi- (icosa- when alone)		2	-di-
30	triaconta-		3	-tri-
40	tetraconta-		4	-tetra-
50	pentaconta-		5	-penta-
60	hexaconta-		6	-hexa-
70	heptaconta-		7	-hepta-
80	octaconta-		8	-octa-
90	enneaconta-		9	-ennea-

Extending the system up to 999 is expressed with these prefixes.^[1]

Ones
Tens		Twenties		Thirties+		Hundreds
		10	deca-	20	icosa-	30	triaconta-
1	hena-	11	hendeca-	21	icosi-hena-	31	triaconta-hena-	100	hecta-
2	di-	12	dodeca-	22	icosi-di-	32	triaconta-di-	200	dihecta-
3	tri-	13	triskaideca-	23	icosi-tri-	33	triaconta-tri-	300	trihecta-
4	tetra-	14	tetrakaideca-	24	icosi-tetra-	40	tetraconta-	400	tetrahecta-
5	penta-	15	pentakaideca-	25	icosi-penta-	50	pentaconta-	500	pentahecta-
6	hexa-	16	hexakaideca-	26	icosi-hexa-	60	hexaconta-	600	hexahecta-
7	hepta-	17	heptakaideca-	27	icosi-hepta-	70	heptaconta-	700	heptahecta-
8	octa-	18	octakaideca-	28	icosi-octa-	80	octaconta-	800	octahecta-
9	ennea-	19	enneakaideca-	29	icosi-ennea-	90	enneaconta-	900	enneahecta-

List of n-gons by Greek numerical prefixes

Names
1	henagon	monogon
2	digon	bigon
3	trigon	triangle
4	tetragon	quadrilateral
5	pentagon
6	hexagon
7	heptagon	septagon
8	octagon
9	enneagon	nonagon
10	decagon
11	hendecagon	undecagon
12	dodecagon
13	tridecagon	triskaidecagon
14	tetradecagon	tetrakaidecagon
15	pentadecagon	pentakaidecagon
16	hexadecagon	hexakaidecagon
17	heptadecagon	heptakaidecagon
18	octadecagon	octakaidecagon
19	enneadecagon	enneakaidecagon
20	icosagon
21	icosikaihenagon	icosihenagon
22	icosikaidigon	icosidigon	icosadigon
23	icosikaitrigon	icositrigon	icosatrigon
24	icosikaitetragon	icositetragon	icosatetragon
25	icosikaipentagon	icosipentagon	icosapentagon
26	icosikaihexagon	icosihexagon	icosahexagon
27	icosikaiheptagon	icosiheptagon	icosaheptagon
28	icosikaioctagon	icosioctagon	icosaoctagon
29	icosikaienneagon	icosienneagon	icosaenneagon
30	triacontagon
31	triacontakaihenagon	triacontahenagon	tricontahenagon
32	triacontakaidigon	triacontadigon	tricontadigon
33	triacontakaitrigon	triacontatrigon	tricontatrigon
34	triacontakaitetragon	triacontatetragon	tricontatetragon
35	triacontakaipentagon	triacontapentagon	tricontapentagon
36	triacontakaihexagon	triacontahexagon	tricontahexagon
37	triacontakaiheptagon	triacontaheptagon	tricontaheptagon
38	triacontakaioctagon	triacontaoctagon	tricontaoctagon
39	triacontakaienneagon	triacontaenneagon	tricontaenneagon
40	tetracontagon		tessaracontagon
41	tetracontakaihenagon	tetracontahenagon	tessaracontahenagon
42	tetracontakaidigon	tetracontadigon	tessaracontadigon
43	tetracontakaitrigon	tetracontatrigon	tessaracontatrigon
44	tetracontakaitetragon	tetracontatetragon	tessaracontatetragon
45	tetracontakaipentagon	tetracontapentagon	tessaracontapentagon
46	tetracontakaihexagon	tetracontahexagon	tessaracontahexagon
47	tetracontakaiheptagon	tetracontaheptagon	tessaracontaheptagon
48	tetracontakaioctagon	tetracontaoctagon	tessaracontaoctagon
49	tetracontakaienneagon	tetracontaenneagon	tessaracontaenneagon
50	pentacontagon		pentecontagon
51	pentacontakaihenagon	pentacontahenagon	pentecontahenagon
52	pentacontakaidigon	pentacontadigon	pentecontadigon
53	pentacontakaitrigon	pentacontatrigon	pentecontatrigon
54	pentacontakaitetragon	pentacontatetragon	pentecontatetragon
55	pentacontakaipentagon	pentacontapentagon	pentecontapentagon
56	pentacontakaihexagon	pentacontahexagon	pentecontahexagon
57	pentacontakaiheptagon	pentacontaheptagon	pentecontaheptagon
58	pentacontakaioctagon	pentacontaoctagon	pentecontaoctagon
59	pentacontakaienneagon	pentacontaenneagon	pentecontaenneagon
60	hexacontagon		hexecontagon
61	hexacontakaihenagon	hexacontahenagon	hexecontahenagon
62	hexacontakaidigon	hexacontadigon	hexecontadigon
63	hexacontakaitrigon	hexacontatrigon	hexecontatrigon
64	hexacontakaitetragon	hexacontatetragon	hexecontatetragon
65	hexacontakaipentagon	hexacontapentagon	hexecontapentagon
66	hexacontakaihexagon	hexacontahexagon	hexecontahexagon
67	hexacontakaiheptagon	hexacontaheptagon	hexecontaheptagon
68	hexacontakaioctagon	hexacontaoctagon	hexecontaoctagon
69	hexacontakaienneagon	hexacontaenneagon	hexecontaenneagon
70	heptacontagon		hebdomecontagon
71	heptacontakaihenagon	heptacontahenagon	hebdomecontahenagon
72	heptacontakaidigon	heptacontadigon	hebdomecontadigon
73	heptacontakaitrigon	heptacontatrigon	hebdomecontatrigon
74	heptacontakaitetragon	heptacontatetragon	hebdomecontatetragon
75	heptacontakaipentagon	heptacontapentagon	hebdomecontapentagon
76	heptacontakaihexagon	heptacontahexagon	hebdomecontahexagon
77	heptacontakaiheptagon	heptacontaheptagon	hebdomecontaheptagon
78	heptacontakaioctagon	heptacontaoctagon	hebdomecontaoctagon
79	heptacontakaienneagon	heptacontaenneagon	hebdomecontaenneagon
80	octacontagon		ogdoecontagon
81	octacontakaihenagon	octacontahenagon	ogdoecontahenagon
82	octacontakaidigon	octacontadigon	ogdoecontadigon
83	octacontakaitrigon	octacontatrigon	ogdoecontatrigon
84	octacontakaitetragon	octacontatetragon	ogdoecontatetragon
85	octacontakaipentagon	octacontapentagon	ogdoecontapentagon
86	octacontakaihexagon	octacontahexagon	ogdoecontahexagon
87	octacontakaiheptagon	octacontaheptagon	ogdoecontaheptagon
88	octacontakaioctagon	octacontaoctagon	ogdoecontaoctagon
89	octacontakaienneagon	octacontaenneagon	ogdoecontaenneagon
90	enneacontagon		enenecontagon
91	enneacontakaihenagon	enneacontahenagon	enenecontahenagon
92	enneacontakaidigon	enneacontadigon	enenecontadigon
93	enneacontakaitrigon	enneacontatrigon	enenecontatrigon
94	enneacontakaitetragon	enneacontatetragon	enenecontatetragon
95	enneacontakaipentagon	enneacontapentagon	enenecontapentagon
96	enneacontakaihexagon	enneacontahexagon	enenecontahexagon
97	enneacontakaiheptagon	enneacontaheptagon	enenecontaheptagon
98	enneacontakaioctagon	enneacontaoctagon	enenecontaoctagon
99	enneacontakaienneagon	enneacontaenneagon	enenecontaenneagon
100	hectogon	hecatontagon	hecatogon
120	120-gon	hecatonicosagon	dodecacontagon
200	dihectagon		diacosigon
300	trihectagon		triacosigon
400	tetrahectagon		tetracosigon
500	pentahectagon		pentacosigon
600	hexahectagon		hexacosigon
700	heptahectagon		heptacosigon
800	octahectagon		octacosigon
900	enneahectagon		enacosigon
	chiliagon
	dischiliagon	Dischiliagon	dichiliagon
	trischiliagon	Trischiliagon	trichiliagon
	tetrakischiliagon	tetrachiliagon
	pentakischiliagon	pentachiliagon
	hexakischiliagon	hexachiliagon
	heptakischiliagon	heptachiliagon
	octakischiliagon	octachiliagon
	enneakischiliagon	enneachilliagon
	myriagon
	dismyriagon	dimyriagon
	trismyriagon	trimyriagon
	tetrakismyriagon	tetramyriagon
	pentakismyriagon	pentamyriagon
	hexakismyriagon	hexamyriagon
	heptakismyriagon	heptamyriagon
	octakismyriagon	octamyriagon
	enneakismyriagon	enneamyriagon
	decakismyriagon	decamyriagon
	icosakismyriagon	icosamyriagon
	triacontakismyriagon	tricontamyriagon
	tetracontakismyriagon	tetracontamyriagon
	pentacontakismyriagon	pentacontamyriagon
	hexacontakismyriagon	hexacontamyriagon
	heptacontakismyriagon	heptacontamyriagon
	octacontakismyriagon	octacontamyriagon
	enneacontakismyriagon	enneacontamyriagon
	hecatontakismyriagon	megagon
	diacosakismyriagon	dimegagon
	triacosakismyriagon	trimegagon
	tetracosakismyriagon	tetramegagon
	pentacosakismyriagon	pentamegagon
	hexacosakismyriagon	hexamegagon
	heptacosakismyriagon	heptamegagon
	octacosakismyriagon	octamegagon
	enneacosakismyriagon	enneamegagon
	chiliakismyriagon	decamegagon
	dischiliakismyriagon	icosamegagon
	trischiliakismyriagon	triacontamegagon
	tetrakischiliakismyriagon	tetracontamegagon
	pentakischiliakismyriagon	pentacontamegagon
	hexakischiliakismyriagon	hexacontamegagon
	heptakischiliakismyriagon	heptacontamegagon
	octakischiliakismyriagon	octacontamegagon
	enneakischiliakismyriagon	enneacontamegagon
	myriakismyriagon	hectamegagon
∞	apeirogon

References

NAMING POLYGONS
Benjamin Franklin Finkel, A Mathematical Solution Book Containing Systematic Solutions to Many of the Most Difficult Problems, 1888

Notes and References

Web site: Naming Polygons and Polyhedra . The Math Forum . Drexel University . 2015-02-13 . 2013-05-25 . https://web.archive.org/web/20130525061110/http://mathforum.org/dr.math/faq/faq.polygon.names.html . live .