- a substance, such as a reagent, that undergoes a reaction
- short for nuclear reactor
- a vessel, esp one in industrial use, in which a chemical reaction takes place
- a coil of low resistance and high inductance that introduces reactance into a circuit
- a person sensitive to a particular drug or agent
WordReference Random House Learner's Dictionary of American English © 2026
re•ac•tor /riˈæktɚ/USA pronunciation
n.
WordReference Random House Unabridged Dictionary of American English © 2026- [countable]
- one that reacts.
- Energy, Physicsan apparatus in which a nuclear-fission chain reaction is sustained and controlled.
re•ac•tor
(rē ak′tər),USA pronunciation n.
- a person or thing that reacts or undergoes reaction.
- [Elect.]a device whose primary purpose is to introduce reactance into a circuit.
- Immunology, Veterinary Diseasesa patient or animal that reacts positively towards a foreign material.
- Energy, PhysicsAlso called atomic pile, chain reactor, chain-reacting pile, nuclear reactor, pile. [Physics.]an apparatus in which a nuclear-fission chain reaction can be initiated, sustained, and controlled, for generating heat or producing useful radiation.
- Chemistry(esp. in industry) a large container, as a vat, for processes in which the substances involved undergo a chemical reaction.
- 1885–90; 1940–45 for def. 4; react + -or2
Collins Concise English Dictionary © HarperCollins Publishers::
reactor /rɪˈæktə/ n
'reactor' also found in these entries (note: many are not synonyms or translations):
advanced gas-cooled reactor
- AGR
- atomic pile
- boiling-water reactor
- breeder
- breeder reactor
- calandria
- Chernobyl
- conversion
- converter
- converter reactor
- core
- critical
- criticality
- crud
- Culham
- decommission
- doughnut
- Dounreay
- fast-breeder reactor
- fuel
- gas-cooled reactor
- intermediate-level waste
- magnox reactor
- meltdown
- nuclear power
- nuclear reactor
- pile
- plutonium
- poison
- pressurized-water reactor
- PWR
- scram
- shield
- thermal reactor
- tokamak
- tritium
- varactor
- absorber
- afterheat
- atomic reactor
- bioreactor
- breed
- breeding
- burnup
- catalytic cracking
- chain-reacting pile
- chain reactor
- China syndrome
- collision density