[ toh-kuh-mak, tok-uh- ]
/ ˈtoʊ kəˌmæk, ˈtɒk ə- /

noun Physics.

a type of experimental nuclear fusion reactor in which a plasma of atoms circulates in a toroidal tube and is confined to a narrow beam by an electromagnetic field.

Nearby words

  1. toise,
  2. toitoi,
  3. tojo,
  4. tojo, hideki,
  5. tok pisin,
  6. tokara islands,
  7. tokay,
  8. toke,
  9. tokelau,
  10. tokelau islands

Origin of tokamak

1960–65; < Russian tokamák, acronym from toroidálʾnaya kámera s aksiálʾnym magnítnym pólem toroidal chamber with an axial magnetic field Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for tokamak


/ (ˈtɒkəˌmæk) /


physics a toroidal reactor used in thermonuclear experiments, in which a strong helical magnetic field keeps the plasma from contacting the external walls. The magnetic field is produced partly by current-carrying coils and partly by a large inductively driven current through the plasma

Word Origin for tokamak

C20: from Russian to (roidál'naya) kám (era s) ak (siál'nym magnitnym pólem), toroidal chamber with magnetic field

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012