particle

1. (physics) Any of various physical objects making up the constituent parts of an atom; an elementary particle or subatomic particle.Examples: "What, he asked himself, does quantum theory have to say about the familiar properties of particles such as position?"; "The physics of elementary particles in the 20th century was distinguished by the observation of particles whose existence had been predicted by theorists sometimes decades earlier."

2. (grammar) A part of speech that has no inherent lexical definition but must be associated with another word to impart meaning, often a grammatical category: for example, the English word to in a full infinitive phrase (to eat) or O in a vocative phrase (O Canada), or as a discourse marker (mmm).Examples: "In English there is no grammatical device to differentiate predicational judgments from nonpredicational descriptions. This distinction does cast a shadow on the grammatical sphere to some extent, but recognition of it must generally be made in semantic terms. It is maintained here that in Japanese, on the other hand, the distinction is grammatically realized through the use of the two particles wa and ga."; "Traditional grammar typically recognises a number of further categories: for example, in his Reference Book of Terms in Traditional Grammar for Language Students, Simpson (1982) posits two additional word-level categories which he refers to as Particle, and Conjunction. Particles include the italicised words {...} (a) He put his hat on (b) If you pull too hard, the handle will come off (c) He was leaning too far over the side, and fell out (d) He went up to see the manager"Synonyms: p-word

3. (linguistics) A part of speech which cannot be inflected.Examples: "322. The parts of speech which are neither declined nor conjugated, are called by the general name of particles. 323. They are adverbs, prepositions, conjunctions, and interjections."; "The Parts of Speech are the Noun (Substantive and Adjective), the Pronoun, the Verb, and the Particles (Adverb, Preposition, and Conjunction)[.]"

4. (Christianity) In the Roman Catholic church, a crumb of consecrated bread; also the smaller breads used in the communion of the laity.