noun · 10 senses · updated from the 2026-07-25 local source snapshot
Definitions and examples are grouped by meaning. Pronunciation, history, word forms, translations, descendants, synonyms, antonyms, derived terms, and related words appear whenever the source provides them.
Sound
Pronunciation
Each Play button uses your device's default local English voice, or a natural local fallback. The selected voice name appears after playback. This is synthesized speech, not a source recording.
Received-Pronunciation:/ˈmɛltdaʊn/
British, Southern, Standard:/ˈmɛltdawn/
General-American:/ˈmɛltˌdaʊn/
General-American:Recorded audio is listed in the source snapshot.
CMU ARPABET:M EH1 L T D AW2 N
Digits mark lexical stress: 1 primary, 2 secondary, 0 unstressed.
1
noun
Meaning 1
An act or process of melting.
Definition source: English Wiktionary via Wiktextract
Usage: countable
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
2
noun
Meaning 2
An act or process of melting.
Severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor, with the potential for radiation to escape; (countable) an instance of this.
Definition source: English Wiktionary via Wiktextract
Usage: uncountable
Qualifier: nuclear energy
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
3
noun
Meaning 3
A mass of melted material.
Definition source: English Wiktionary via Wiktextract
Usage: countable, rare
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
4
noun
Meaning 4
Chiefly preceded by a descriptive word: uncontrolled disorder which often has disastrous consequences; (countable) a situation involving this; a crisis.
Definition source: English Wiktionary via Wiktextract
Usage: figuratively, uncountable
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: none provided
Antonyms: none provided
5
noun
Meaning 5
Chiefly preceded by a descriptive word: uncontrolled disorder which often has disastrous consequences; (countable) a situation involving this; a crisis.
Synonym of crash (“a sudden large decline in the value of money, stocks or other assets, etc., especially one that causes additional economic difficulties”).
Definition source: English Wiktionary via Wiktextract
Usage: countable, figuratively
Topics: business, finance
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: crash
Antonyms: none provided
6
noun
Meaning 6
(Sudden) loss of control over one's behaviour, emotions, etc.; (countable) an instance of this.
An emotional outburst; a fit, a tantrum.
Definition source: English Wiktionary via Wiktextract
Usage: countable, figuratively, informal
No example sentence was provided for this meaning.
(Sudden) loss of control over one's behaviour, emotions, etc.; (countable) an instance of this.
A response to sensory overload or stress, in which an autistic person is overwhelmed by intense, seemingly disproportionate emotions, behaving erratically and becoming unable to mask (“act more neurotypically”).
Definition source: English Wiktionary via Wiktextract
Usage: countable, figuratively, informal
Qualifier: autism
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: melty
Antonyms: none provided
8
noun
Meaning 8
(Sudden) loss of control over one's behaviour, emotions, etc.; (countable) an instance of this.
Synonym of nervous breakdown (“an attack of a psychological disorder such as anxiety or depression which is so severe that it prevents a person from continuing to function normally”); also (loosely), a situation where one is unable to function mentally due to panic, stress, etc.
Definition source: English Wiktionary via Wiktextract
Usage: countable, figuratively, informal
Topics: human-sciences, psychology, sciences
No example sentence was provided for this meaning.
severe overheating of the core of a nuclear reactor resulting in the core melting and radiation escaping
Definition source: Princeton WordNet 3.0
No example sentence was provided for this meaning.
Meaning relationships
Synonyms: nuclear meltdown
Antonyms: none provided
Broader terms: overheating
History
Etymology
From melt (verb) + down (adverb), a deverbal from melt down (verb).
Across languages
Translations
75 source translations are retained for this English entry.
Bulgarian:
стопя́ване
(stopjávane)
— act or process of melting
Finnish:
sulaminen
— act or process of melting
Finnish:
sulanut massa
— mass of melted material
Angika:
नाभिकीय गलाव
(nābhikīya galāv)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Arabic:
اِنْصِهَار نَوَوِيّ
(inṣihār nawawiyy)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Armenian:
ռեակտորի միջուկի հալում
(ṙeaktori miǰuki halum)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Armenian:
մելտդաուն
(meltdaun)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Basque:
nukleoaren fusioa
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Basque:
nukleo-fusioa
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Bulgarian:
разтопя́ване на акти́вната зо́на
(raztopjávane na aktívnata zóna)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Bulgarian:
разтопя́ване
(raztopjávane)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Catalan:
fusió de nucli
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Chinese Mandarin:
堆芯熔毀 /堆芯熔毁
(duīxīn rónghuǐ)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Czech:
roztavení reaktoru
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Danish:
nedsmeltning
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Dutch:
kernsmelting
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Finnish:
reaktoriytimen sulaminen
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Finnish:
sulaminen
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
French:
fusion du cœur d'un réacteur nucléaire
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
German:
Kernschmelze
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Greek:
τήξη
(tíxi)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Hebrew:
התכה
(hatakhá)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Hindi:
नाभिकीय गलाव
(nābhikīya galāv)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Hungarian:
zónaolvadás
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Indonesian:
kebocoran nuklir
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Irish:
leá iomlán
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Italian:
fusione del nocciolo
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Japanese:
メルトダウン
(merutodaun)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Japanese:
炉心熔融
(roshin-yōyū)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Korean:
노심 용해
(nosim yonghae)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Low German:
Karnsmölt
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Malay:
peleburan nuklear
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Norwegian Bokmål:
kjernefysisk nedsmelting
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Norwegian Nynorsk:
kjernefysisk nedsmelting
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Persian:
ذوبشدن سوخت هستهای
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Polish:
stopienie rdzenia reaktora jądrowego
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Portuguese:
derretimento nuclear
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Romanian:
topire
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Russian:
мелтда́ун
(mɛltdáun)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Russian:
расплавле́ние
(rasplavlénije)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Russian:
разруше́ние и́з-за расплавле́ния
(razrušénije íz-za rasplavlénija)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Serbo-Croatian:
taljenje jezgre
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Spanish:
copelación/fundición nuclear
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Spanish:
derretimiento nuclear
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Spanish:
fusión de núcleo
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Swedish:
härdsmälta
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Tagalog:
nukleyar na pagkatunaw
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Tagalog:
pagkalusaw na nukleyar
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Tamil:
அணுக்கரு உருகல்
(aṇukkaru urukal)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Thai:
การหลอมละลายนิวเคลียร์
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Turkish:
nükleer erime
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Ukrainian:
розплавлення
(rozplavlennya)
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Vietnamese:
nóng chảy hạt nhân
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Welsh:
toddiad niwclear
— severe uncontrolled overheating and melting of the fuel in the core of a nuclear reactor
Bulgarian:
и́зблик
(ízblik)
— (sudden) loss of control over one’s behaviour, emotions, etc.; an instance of this
Bulgarian:
при́стъп
(prístǎp)
— (sudden) loss of control over one’s behaviour, emotions, etc.; an instance of this
Finnish:
purkaus
— (sudden) loss of control over one’s behaviour, emotions, etc.; an instance of this
Finnish:
räjähdys
— (sudden) loss of control over one’s behaviour, emotions, etc.; an instance of this
Finnish:
tunneromahdus
— autistic response to sensory overload or stress
Danish:
nedsmeltning
— situation where one is unable to function mentally due to panic, stress, etc.
Finnish:
romahdus
— situation where one is unable to function mentally due to panic, stress, etc.
German:
Nervenzusammenbruch
— situation where one is unable to function mentally due to panic, stress, etc.
German:
Zusammenbruch
— situation where one is unable to function mentally due to panic, stress, etc.
Hebrew:
מלטדאון
(méltdaun)
— situation where one is unable to function mentally due to panic, stress, etc.
Hebrew:
התמוטטות
(hitmotetút)
— situation where one is unable to function mentally due to panic, stress, etc.
Hebrew:
התמוטטות עצבים
(hitmotetút atsabím)
— situation where one is unable to function mentally due to panic, stress, etc.
Hebrew:
קריסה
(krisá)
— situation where one is unable to function mentally due to panic, stress, etc.
Portuguese:
catástrofe
— situation where one is unable to function mentally due to panic, stress, etc.
Romanian:
criză
— situation where one is unable to function mentally due to panic, stress, etc.
Russian:
встря́ска
(vstrjáska)
— situation where one is unable to function mentally due to panic, stress, etc.
Serbo-Croatian:
eratično stanje
— situation where one is unable to function mentally due to panic, stress, etc.
Spanish:
chiripiolca
— situation where one is unable to function mentally due to panic, stress, etc.
Spanish:
chiripiorca
— situation where one is unable to function mentally due to panic, stress, etc.
Spanish:
chucaque
— situation where one is unable to function mentally due to panic, stress, etc.
Spanish:
corajina
— situation where one is unable to function mentally due to panic, stress, etc.