[ noo-klee-er, nyoo- or, by metathesis, -kyuh-ler ]
/ ˈnu kli ər, ˈnyu- or, by metathesis, -kyə lər /


pertaining to or involving atomic weapons: nuclear war.
operated or powered by atomic energy: a nuclear submarine.
(of a nation or group of nations) having atomic weapons.
of, relating to, or forming a nucleus.
of, relating to, or like the nuclear family: nuclear bonds.

noun Informal.

nuclear energy: switching to nuclear as a power source.

Origin of nuclear

1840–50; nucle(us) + -ar1; compare French nucléaire

pronunciation note for nuclear

In pronouncing nuclear, the second and third syllables are most commonly said as [-klee-er] /-kli ər/, a sequence of sounds that directly reflects the spelled sequence ‐cle · ar. In recent years, a somewhat controversial pronunciation has come to public attention, with these two final syllables said as [-kyuh-ler] /-kyə lər/. Since [-klee-er] /-kli ər/, the common pronunciation of ‐cle · ar, might also be represented, broadly, as [-kluh-yer] /-klə yər/, the [-kyuh-ler] /-kyə lər/ pronunciation can be seen as coming from a process of metathesis, in which the [l] /l/ and the [y] /y/ change places. The resulting pronunciation is reinforced by analogy with such words as molecular, particular, and muscular, and although it occurs with some frequency among highly educated speakers, including scientists, professors, and government officials, it is disapproved of by many.


in·ter·nu·cle·ar, adjective mul·ti·nu·cle·ar, adjective post·nu·cle·ar, adjective

Example sentences from the Web for nuclear

British Dictionary definitions for nuclear

/ (ˈnjuːklɪə) /


of, concerned with, or involving the nucleus of an atom nuclear fission
biology of, relating to, or contained within the nucleus of a cell a nuclear membrane
of, relating to, forming, or resembling any other kind of nucleus
of, concerned with, or operated by energy from fission or fusion of atomic nuclei a nuclear weapon
involving, concerned with, or possessing nuclear weapons nuclear war; a nuclear strike

Medical definitions for nuclear

[ nōōklē-ər ]


Of or forming a nucleus.
Of or relating to atomic nuclei.

Scientific definitions for nuclear

[ nōōklē-ər ]

Relating to or forming a cell nucleus.
Relating to atomic nuclei.
Using energy derived from the nuclei of atoms through fission or fusion reactions.