What does "ket" mean?

A column vector, in Hilbert space, especially as representing the state of a quantum mechanical system; the complex conjugate transpose of a bra (a row vector); a ket vector. Symbolised by |...〉.

What is a synonym for "ket"?

Common synonyms include: brusseler, english, kettish, language.

Ket

//kɛt// name, noun, slang

name, noun, slang ·Moderate ·High school level

Definitions

Noun

1
A column vector, in Hilbert space, especially as representing the state of a quantum mechanical system; the complex conjugate transpose of a bra (a row vector); a ket vector. Symbolised by |...〉.
"A particular ket, say #124;A#92;rangle, might be represented by a particular column vector. Its corresponding bra, #92;langleA#124;, would then be represented by the row vector which is the transpose conjugate of that column vector."
2
Carrion; any filth. Northern-England, countable, uncountable
3
ketamine colloquial, uncountable
4
matted wool Scotland, uncountable
5
A member of a people of Krasnoyarsk Krai in Central Siberia, Russia.

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6
A native or inhabitant of Brussels. informal
7
Sweetmeats. Northumbria, countable, uncountable
8
A sweet, treat or candy. Wearside, countable, uncountable

Proper Noun

1
A river in Russia, a tributary of the Ob.
2
The station code of Kennedy Town in Hong Kong.
3
The Yeniseian language of the Ket people.

Synonyms

All synonyms

brusseler english kettish language

Antonyms

All antonyms

bra

Example

More examples

"A particular ket, say #124;A#92;rangle, might be represented by a particular column vector. Its corresponding bra, #92;langleA#124;, would then be represented by the row vector which is the transpose conjugate of that column vector."

Etymology

Etymology 1

From bra-ket notation invented by Paul Dirac, from bracket.

Etymology 2

Probably of Old Norse origin like kjǫt (“meat”), from Proto-Germanic *ketwą. Compare Icelandic kjöt (“flesh”); akin to Swedish kött, Danish kød, and Norwegian kjøtt. The use of the term ket for "candy" or "sweets" probably derived from its use to describe sweet meats or as a deterrent to children.

Etymology 3

Clipping of ketamine.

Etymology 4

Learned borrowing from Ket кеʼт (keˀt, “human being”), via Russian.

Etymology 5

Borrowed from Dutch Ket, derived from Dutch ket, Middle Dutch *kitte, Proto-West Germanic *kitte.

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Data sourced from Wiktionary, WordNet, CMU, and other open linguistic databases. Updated March 2026.

Ket