خائوس یا آشفتگی ازلی (به یونانی: Χαος Χαεος, khaos) (در کاربرد ترجمه یونانی کلاسیک و فلسفه: بُن آشوب، در کاربرد امروزی: دُش آمیختگی)، نخستین مخلوق در اساطیر یونانی، آشکارا تهیگی گستردهای بود که وضعیت ابتدایی پیش از آفرینش را بیان میکرد. البته در این داستانها در اشارههایی خائوس دارای شخصیتی انسانی تصویر شدهاست. خائوس را همچنین در افسانههای یونانی تودهٔ بیشکل و درهم و برهم عوامل، که پیش از آفرینش جهان را فرا گرفته بود نامیدند. در الهیات نیز خلأ اولیه و آشفتگی عوامل کائنات قبل از خلقت تحت عنوان هیولا خوانده شدهاست.
نقشمایه نبرد با خائوس در همهٔ این افسانهها دیده میشود که حاکی از مبارزهٔ یک خداوند دلاور با هیولای آشوب و بیسامانی و هرج و مرجی (اغلب در قالب یک مار یا اژدها) است. لفظ مذکور در دینهای باستانی خاور نزدیک به مفهومهای مشابه بسط یافتهاست. این مفهوم نخستین بار در آثار هزیود، شاعر مشهور یونانی مطرح شدهاست، اما احتمال دارد که هزیود این مفهوم را از بابل باستان گرفته باشد.
در افسانههای یونان در ابتدای آفرینش خلاء یا خائوس به وجود آمد یا در واقع به وجود نیامد، زیرا خائوس چیزی نیست که وجود داشته باشد یا نداشته باشد. البته در آن دسته از داستانهایی که خائوس دارای شخصیت است احتمالاً این برداشت میشود که وجود او چیزی نزدیک به وجود خدا بوده باشد (یعنی وجود دارد ولی جسم ندارد). از خائوس زمین یا گایا به وجود آمد بعد به ترتیب تارتاروس که دنیای زیرین است و اروس یا شهوت از خلاء به وجود آمدند. دیگر خدایان به وجود آمده از خائوس عبارتند از تاریکی یا اربوس و الههٔ شب یا نوکس، و اما از ازدواج آنها همرا (روز) و روشنایی یا آیتر متولد شدند. از ازدواج گایا و اورانوس یا همان آسمان نخستین ایزدان پدید آمدند: تایتانهای غولآسا، سیکلوپها و سه هکاتونکایر (غولانی که هر یک صد دست و پنجاه سر داشتند). وقتی اورانوس آنها را در جهان زیرزمینی به بند کرد، گایا جوانترین تیتان، یعنی کرونوس را وا داشت که پدرش را اخته کند و قدرت را برباید.
خائوس منبع الهامی برای نامگذاری سیستم خاصی در ریاضی شده که گاه به صورت آشوبی هم برگردانده شدهاست.
It may also mean space, the expanse of air, the nether abyss or infinite darkness.Pherecydes of Syros (fl. 6th century BC) interprets chaos as water, like something formless which can be differentiated.
Chaos by George Frederic Watts
Hesiod and the Pre-Socratics use the Greek term in the context of cosmogony. Hesiod's Chaos has been interpreted as either
"the gaping void above the Earth created when Earth and Sky are separated from their primordial unity" or "the gaping space below the Earth on which Earth rests".
In Hesiod's Theogony, Chaos was the first thing to exist: "at first Chaos came to be" (or was) but next (possibly out of Chaos) came Gaia, Tartarus and Eros (elsewhere the son of Aphrodite). Unambiguously "born" from Chaos were Erebus and Nyx. For Hesiod, Chaos, like Tartarus, though personified enough to have borne children, was also a place, far away, underground and "gloomy", beyond which lived the Titans. And, like the earth, the ocean, and the upper air, it was also capable of being affected by Zeus' thunderbolts.
Passages in Hesiod's Theogony suggest that Chaos was located below Earth but above Tartarus. Primal Chaos was sometimes said to be the true foundation of reality, particularly by philosophers such as Heraclitus.
The notion of the temporal infinity was familiar to the Greek mind from remote antiquity in the religious conception of immortality.[clarification needed] This idea of the divine as an origin[clarification needed] influenced the first Greek philosophers. The main object of the first efforts to explain the world remained the description of its growth, from a beginning. They believed that the world arose out from a primal unity, and that this substance was the permanent base of all its being. Anaximander claims that the origin is apeiron (the unlimited), a divine and perpetual substance less definite than the common elements. Everything is generated from apeiron, and must return there according to necessity. A conception of the nature of the world was that the earth below its surface stretches down indefinitely and has its roots on or above Tartarus, the lower part of the underworld. In a phrase of Xenophanes, "The upper limit of the earth borders on air, near our feet. The lower limit reaches down to the "apeiron" (i.e. the unlimited)." The sources and limits of the earth, the sea, the sky, Tartarus, and all things are located in a great windy-gap, which seems to be infinite, and is a later specification of "chaos".
In Aristophanes's comedy Birds, first there was Chaos, Night, Erebus, and Tartarus, from Night came Eros, and from Eros and Chaos came the race of birds.
At the beginning there was only Chaos, Night, dark Erebus, and deep Tartarus. Earth, the air and heaven had no existence. Firstly, blackwinged Night laid a germless egg in the bosom of the infinite deeps of Erebus, and from this, after the revolution of long ages, sprang the graceful Eros with his glittering golden wings, swift as the whirlwinds of the tempest. He mated in deep Tartarus with dark Chaos, winged like himself, and thus hatched forth our race, which was the first to see the light. That of the Immortals did not exist until Eros had brought together all the ingredients of the world, and from their marriage Heaven, Ocean, Earth and the imperishable race of blessed gods sprang into being. Thus our origin is very much older than that of the dwellers in Olympus. We [birds] are the offspring of Eros; there are a thousand proofs to show it. We have wings and we lend assistance to lovers. How many handsome youths, who had sworn to remain insensible, have opened their thighs because of our power and have yielded themselves to their lovers when almost at the end of their youth, being led away by the gift of a quail, a waterfowl, a goose, or a cock.
For Ovid, (1st century BC), in his Metamorphoses, Chaos was an unformed mass, where all the elements were jumbled up together in a "shapeless heap".
Ante mare et terras et quod tegit omnia caelum
unus erat toto naturae vultus in orbe,
quem dixere chaos: rudis indigestaque moles
nec quicquam nisi pondus iners congestaque eodem
non bene iunctarum discordia semina rerum.
Before the ocean and the earth appeared— before the skies had overspread them all—
the face of Nature in a vast expanse was naught but Chaos uniformly waste.
It was a rude and undeveloped mass, that nothing made except a ponderous weight;
and all discordant elements confused, were there congested in a shapeless heap. 
According to Hyginus: "From Mist (Caligine) came Chaos. From Chaos and Mist, came Night (Nox), Day (Dies), Darkness (Erebus), and Ether (Aether)." An Orphic tradition apparently had Chaos as the son of Chronus and Ananke.
The motif of Chaoskampf (German: [ˈkaːɔsˌkampf], "struggle against chaos") is ubiquitous in myth and legend, depicting a battle of a culture hero deity with a chaos monster, often in the shape of a serpent or dragon. The same term has also been extended to parallel concepts in the Middle East and North Africa, such as the abstract conflict of ideas in the Egyptian duality of Maat and Isfet or the battle of Horus and Set.
Chaos has been linked with the term abyss/tohu wa-bohu of Genesis 1:2. The term may refer to a state of non-being prior to creation or to a formless state. In the Book of Genesis, the spirit of God is moving upon the face of the waters, displacing the earlier state of the universe which is likened to a "watery chaos" upon which there is choshek (which translated from the Hebrew is darkness/confusion).
The Septuagint makes no use of χάος in the context of creation, instead using the term for גיא, "cleft, gorge, chasm", in Micah 1:6 and Zacharia 14:4.
The Vulgate, however, renders the χάσμα μέγα or "great gulf" between heaven and hell in Luke 16:26 as chaos magnum.
Ramon Llull (1232–1315) wrote a Liber Chaos, in which he identifies Chaos as the primal form or matter created by God. Swiss alchemist Paracelsus (1493–1541) uses chaos synonymously with "classical element" (because the primeval chaos is imagined as a formless congestion of all elements). Paracelsus thus identifies Earth as "the chaos of the gnomi", i.e., the element of the gnomes, through which these spirits move unobstructed as fish do through water, or birds through air. An alchemical treatise by Heinrich Khunrath, printed in Frankfurt in 1708, was entitled Chaos. The 1708 introduction states that the treatise was written in 1597 in Magdeburg, in the author's 23rd year of practicing alchemy. The treatise purports to quote Paracelsus on the point that "The light of the soul, by the will of the Triune God, made all earthly things appear from the primal Chaos."Martin Ruland the Younger, in his 1612 Lexicon Alchemiae, states, "A crude mixture of matter or another name for Materia Prima is Chaos, as it is in the Beginning."
The term gas in chemistry was coined by Dutch chemist Jan Baptist van Helmont in the 17th century directly based on the Paracelsian notion of chaos. The g in gas is due to the Dutch pronunciation of this letter as a spirant, also employed to pronounce Greek χ.
The term chaos has been adopted in modern comparative mythology and religious studies as referring to the primordial state before creation, strictly combining two separate notions of primordial waters or a primordial darkness from which a new order emerges and a primordial state as a merging of opposites, such as heaven and earth, which must be separated by a creator deity in an act of cosmogony. In both cases, chaos referring to a notion of a primordial state contains the cosmos in potentia but needs to be formed by a demiurge before the world can begin its existence.
Use of chaos in the derived sense of "complete disorder or confusion" first appears in Elizabethan Early Modern English, originally implying satirical exaggeration.
"Chaos" in the well-defined sense of chaotic complex system is in turn derived from this usage.
^West, p. 192 line 116 Χάος, "best translated Chasm"; English chasm is a loan from Greek χάσμα, which is root-cognate with χάος.
Most, p. 13, translates Χάος as "Chasm", and notes: (n. 7): "Usually translated as 'Chaos'; but that suggests to us, misleadingly, a jumble of disordered matter, whereas Hesiod's term indicates instead a gap or opening".
^R. S. P. Beekes, Etymological Dictionary of Greek, Brill, 2009, pp. 1614 and 1616–7.
^According to Gantz (1996, p. 4): "With regard to all three of these figures—Gaia, Tartaros, and Eros—we should note that Hesiod does not say they arose from (as opposed to after) Chaos, although this is often assumed." For example, Morford, p. 57, makes these three descendants of Chaos saying they came "presumably out of Chaos, just as Hesiod actually states that 'from Chaos' came Erebus and dark Night". Tripp, p. 159, says simply that Gaia, Tartarus and Eros came "out of Chaos, or together with it". Caldwell, p. 33 n. 116–122, however interprets Hesiod as saying that Chaos, Gaia, Tartarus, and Eros all "are spontaneously generated without source or cause". Later writers commonly make Eros the son of Aphrodite and Ares, though several other parentages are also given, Gantz (1996, pp. 4–5)
^Hyginus. Fabulae,Preface, translated by Smith and Trzaskoma, p. 95. According to Bremmer (2008, p. 5) who translates Caligine as "Darkness": "Hyginus ... started his Fabulae with a strange hodgepodge of Greek and Roman cosmogonies and early genealogies. It begins as follows: Ex Caligine Chaos. Ex Chao et Caligine Nox Dies Erebus Aether (Praefatio 1). His genealogy looks like a derivation from Hesiod, but it starts with the un-Hesiodic and un-Roman Caligo, ‘Darkness’. Darkness probably did occur in a cosmogonic poem of Alcman, but it seems only fair to say that it was not prominent in Greek cosmogonies."
^"halitum illum Gas vocavi, non longe a Chao veterum secretum." Ortus Medicinæ, ed. 1652, p. 59a, cited after the Oxford English Dictionary.
^Mircea Eliade, article "Chaos" in Religion in Geschichte und Gegenwart, 3rd ed. vol. 1, Tübingen, 1957, 1640f.
^Stephen Gosson, The schoole of abuse, containing a plesaunt inuectiue against poets, pipers, plaiers, iesters and such like caterpillers of a commonwelth (1579), p. 53 (cited after OED): "They make their volumes no better than [...] a huge Chaos of foule disorder."
Aristophanes (1938). "Birds". In O'Neill, Jr, Eugene (ed.). The Complete Greek Drama. 2. New York: Random House – via Perseus Digital Library.
Szulakowska, Urszula (2000). The alchemy of light: geometry and optics in late Renaissance alchemical illustration. Symbola et Emblemata - Studies in Renaissance and Baroque Symbolism. 10. BRILL. ISBN978-90-04-11690-0.
Wyatt, Nick (2005) . "Arms and the King: The Earliest Allusions to the Chaoskampf Motif and their Implications for the Interpretation of the Ugaritic and Biblical Traditions". There's such divinity doth hedge a king: selected essays of Nicolas Wyatt on royal ideology in Ugaritic and Old Testament literature. Society for Old Testament Study monographs, Ashgate Publishing. pp. 151–190. ISBN978-0-7546-5330-1.