# ket

> English word · Noun · IPA /kɛt/ · frequency rank #50,025

## Definitions
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 |...〉.

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

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/ket