Pleonasm

Pleonasm (/ˈpliːənæzəm/; from Greek (pleonasmós), from (pleon), meaning 'more, too much') is the use of more words or parts of words than are necessary or sufficient for clear expression: examples are black darkness, burning fire. Such redundancy is, by traditional rhetorical criteria, a manifestation of tautology. That being said, people may use a pleonasm for emphasis or because the phrase has already become established in a certain form.

Often, pleonasm is understood to mean a word or phrase which is useless, clichéd, or repetitive, but a pleonasm can also be simply an unremarkable use of idiom. It can aid in achieving a specific linguistic effect, be it social, poetic, or literary. In particular, pleonasm sometimes serves the same function as rhetorical repetition—it can be used to reinforce an idea, contention, or question, rendering writing clearer and easier to understand. Further, pleonasm can serve as a redundancy check: If a word is unknown, misunderstood, or misheard, or the medium of communication is poor—a wireless telephone connection or sloppy handwriting—pleonastic phrases can help ensure that the entire meaning gets across even if some of the words get lost.

Some pleonastic phrases are part of a language's idiom, like "tuna fish" and "safe haven" in English. They are so common that their use is unremarkable and often even unnoticeable for native speakers, although in many cases the redundancy can be dropped with no loss of meaning.

When expressing possibility, English speakers often use potentially pleonastic expressions such as It may be possible or maybe it's possible, where both terms (verb may/adverb maybe and adjective possible) have the same meaning under certain constructions. Many speakers of English use such expressions for possibility in general, such that most instances of such expressions by those speakers are in fact pleonastic. Others, however, use this expression only to indicate a distinction between ontological possibility and epistemic possibility, as in "Both the ontological possibility of X under current conditions and the ontological impossibility of X under current conditions are epistemically possible" (in logical terms, "I am not aware of any facts inconsistent with the truth of proposition X, but I am likewise not aware of any facts inconsistent with the truth of the negation of X"). The habitual use of the double construction to indicate possibility per se is far less widespread among speakers of most other languages (except in Spanish; see examples); rather, almost all speakers of those languages use one term in a single expression:

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