/ ˈpɑːtɪkl; NAmE ˈpɑːrt-/ noun
1.
a very small piece of sth :
particles of dust
dust particles
There was not a particle of evidence (= no evidence at all) to support the case.
2.
( physics ) a very small piece of matter, such as an electron or proton , that is part of an atom
—see also alpha particle , elementary particle
3.
( grammar ) an adverb or a preposition that can combine with a verb to make a phrasal verb :
In 'She tore up the letter', the word 'up' is a particle.
—see also adverbial particle
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WORD ORIGIN
late Middle English : from Latin particula little part, diminutive of pars , part- .