A particle is a part of speech that cannot be inflected, that is it can be neither declined nor conjugated. In Latin, particles are the adverb, the preposition, the conjunction and the interjection (a word that has emotion).
In modern grammar, a particle is a function word that must be associated with another word or phrase to impart meaning, i.e., does not have its own lexical definition. On this definition, particles are a separate part of speech and are distinct from other classes of function words, such as articles, prepositions, conjunctions and adverbs.
Particles are never inflected.
Languages vary widely in how much they use particles, some using them extensively and others more commonly using alternative devices such as prefixes/suffixes, inflection, auxiliary verbs and word order.
Related concepts and ambiguities
Depending on context, the meaning of the term may overlap with such notions as morpheme, marker, or even adverb as in English phrasal verbs such as out in get out. Under a strict definition, which demands that a particle be uninflected, English deictics like this and that would not be classed as such (since they have plurals and are therefore inflected), and neither would Romance articles (since they are inflected for number and gender).
The foregoing assumes that any function word incapable of inflection is by definition a particle. However, that definition conflicts with the statement (above) that particles have no specific lexical function per se, since non-inflecting words that function as articles, prepositions, conjunctions, interjections etc. clearly do have lexical function. The difficulty disappears if particles are taken to be a separate class of words, one of whose characteristics (which they share with some words of other classes) is that they do not inflect.
In different languages
Infinitival and adverbial particles
- the infinitive to, as in to walk, although this can also be viewed as an integral part of the infinitive form of the verb
- adverbial portions of phrasal verbs, such as off in we put it off too long, although these can also be viewed as adverbs or prepositions.
- the negator not, although this is arguably better defined as an adverb.
Interjections, sentence connectors, and conjunctions
If a particle is defined simply as any function word that cannot be inflected, then conjunctions, prepositions and interjections would be classed as particles (at least in English) although they are traditionally classed as separate parts of speech based on their function. According to this definition, the English definite article the would also be a particle as it is uninflected. (Although the indefinite article "a(n)" only changes form for euphony—inserting an N before words that start with a vowel—it can be considered to be inflected since in the plural it is omitted or replaced by "some".)
A German modal particle serves no necessary syntactical function, but expresses the speaker's attitude towards the utterance. Modal particles include ja, halt, doch, aber, denn, schon and others. Some of these also appear in non-particle forms. Aber, for example, is also the conjunction but. In Er ist Amerikaner, aber er spricht gut Deutsch, "He is American, but he speaks good German," aber is a conjunction connecting two sentences. But in Er spricht aber gut Deutsch!, the aber is a particle, with the sentence perhaps best translated as "What good German he speaks!" The particles appear more often in relaxed spoken and casually written registers of German.
In Chinese, particles are one of two major word classes. The other class includes noun, verbs and adjectives. Linguists do not agree on whether or not Chinese pronouns and adverbs should be classified as particles.
Japanese and Korean
The term particle is often used in descriptions of Japanese and Korean, where they are used to mark nouns according to their case or their role (subject, object, complement, or topic) in a sentence or clause. These particles may function as endings and therefore as bound morphemes rather than independent words, in particular in Old Japanese. Some of these particles are best analysed as case markers and some as postpositions. There are sentence-tagging particles such as Japanese and Chinese question markers.
Thai also has particles.
Polynesian languages are almost devoid of inflection, and use particles extensively to indicate mood, tense, and case. Suggs, discussing the deciphering of the rongorongo script of Easter Island, describes them as all-important. In Māori for example, the versatile particle "e" can signal the imperative mood, the vocative case, the future tense, or the subject of a sentence formed with most passive verbs. The particle "i" signals the past imperfect tense, the object of a transitive verb or the subject of a sentence formed with "neuter verbs" (a form of passive verb), as well as the prepositions in, at and from.
- E. A. Andrews: First Lessions in Latin; or Introduction to Andrews and Stoddard's Latin Grammar. 6th edition, Boston, 1844, p.91. Quote: "322. The parts of speech that are neither declined nor conjugated, are called by the general name of particles. 323. They are adverbs, prepositions, conjunctions, and interjections."
- B. L. Gildersleeve & G. Lodge: Gildersleeve's Latin Grammar. Dover, 2008, reprint of the 3rd edition of 1894, p.9. Quote: "The Parts of Speech are the Noun (Substantive and Adjective), the Pronoun, the Verb, and the Particles (Adverb, Preposition, and Conjunction)"
- McArthur, Tom: "The Oxford Companion to the English Language", pp. 72-76, Oxford University Press, 1992. ISBN 0-19-214183-X For various keywords
- http://www.canoo.net/services/OnlineGrammar/Wort/Ueberblick/Flexionslos.html?lang=en&darj=1 Interjections
- Martin Durrell, Using German, Cambridge University Press, 2nd edition (2003), p. 156-164.
- http://japanese.about.com/blparticles.htm List of Japanese particles
- http://www9.georgetown.edu/faculty/portnerp/nsfsite/KoreanParticlesMiokPak.pdf List of Korean particles
- http://siamsmile.webs.com/thaiparticles/thaiparticles.html Large list of Thai particles and exclamations with explanations and example sentences.
- Suggs, Robert C. The Island Civilizations of Polynesia.
- Foster, John. He Whakamarama: A Short Course in Maori.