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proton

noun [C]
 
 
/ˈprəʊ.tɒn/ US  /ˈproʊ.t̬ɑːn/

Definition

a type of elementary particle (= very small piece of matter) that has a positive electrical charge and is found in the nucleus of all atoms → Compare electron, neutronAtoms, molecules and sub-atomic particles
(Definition of proton noun from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press)
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