■ noun
1》 a minute portion of matter.
2》 Physics a subatomic constituent of the physical world, e.g. an electron, proton, neutrino, or photon.
3》 Grammar a minor function word that has comparatively little meaning and does not inflect, e.g. in , up , off , or over used with verbs to make phrasal verbs.
Origin
ME: from L. particula 'little part', dimin. of pars , part- .