Ellipsis

Marked forms of words - Inflection, Derivation, Declension, Conjugation · Diminutive, Augmentative

Groups and categories and properties of words - Syntactic and lexical categories · Grammatical cases · Correlatives · Expletives · Adjuncts

Words and meaning - Morphology · Lexicology · Semiotics · Onomasiology · Figures of speech, expressions, phraseology, etc. · Word similarity · Ambiguity · Modality ·

Segment function, interaction, reference - Clitics · Apposition· Parataxis, Hypotaxis· Attributive· Binding · Coordinations · Word and concept reference

Sentence structure and style - Agreement · Ellipsis· Hedging

Phonology - Articulation · Formants· Prosody · Sound change · Intonation, stress, focus · Diphones · Intervocalic · Glottal stop · Vowel_diagrams · Elision · Ablaut_and_umlaut · Phonics

Analyses, models, processing, software - Minimal pairs · Concordances · Linguistics software · Some_relatively_basic_text_processing · Word embeddings · Semantic similarity ·· Speech processing · Praat notes · Praat plugins and toolkit notes · Praat scripting notes

Unsorted - Contextualism · · Text summarization · Accent, Dialect, Language · Pidgin, Creole · Natural language typology · Writing_systems · Typography, orthography · Digraphs, ligatures, dipthongs · More linguistic terms and descriptions · Phonetic scripts

Leaving stuff out

Ellipsis is the concept and practice of leaving things out.

Usually words, phrases, clauses, or other parts of sentences, and usually because of redundancy, obviousness, or irrelevancy, or to things having a parenthetical sense.

In linguistic analysis, ellipsis is often grammatical and predictable, and is often studied when linguists are interested in describing complete grammars, or grammatical parsing based on such structures (such as discourse analysis, Minimalism, and many others).

It is related to coordination. See also elision.

Gapping

Gapping refers to a strategy of ellipsis of part of a sentence (often a verb or function word) in conjunctions.

In other words: leaving things out where where they are expected to be understood from parallel parts of some other (often earlier) part of that conjunction (usually with very similar meaning).

Example: John studies logic, and Charles phonetics.

(not the best example; it could also be explained in other ways, e.g. "if verb omitted, assume it is the last seen one" which isn't really the same concept)

There are some interesting constraints on gapping. It may be commonly ungrammatical in some languages, or not even particularly exist (e.g. in Chinese (verify)).

Marking that you're leaving stuff out

Ellipsis also refers to the written symbol regularly used to denote various types of ellipsis. (Singular: Ellipsis, plural: ellipses (pronunciation -is and -ees)

It consists of three dots. Commonly written/approximated with three full stop/periods, particularly in absence of a true ellipsis glyph/character.

(...not to be confused with ellipse, the shape, of which the plural is also ellipses, but is not pronounced the same way. See heteronyms)

In modern use, the dots are usually packed tightly, like … in Unicode (codepoint U+2026 (…)).

Uses

Stylistic

Practical use (and style guides) include further uses of the ellipsis character. These include:

a pause in speech: I just... never thought it would go that way.
a lingering end of a sentence: And that's that, I suppose...
marking something to be continued, or a continuation of a previous thought: ...which can also start the sentence without a capital.'
omitting parts of quotes or paraphrases for brevity: I did [...] not think so.

Differences may include necessity of a space, particularly if it marked ommission, while the trailing off may or may not be considered to end a (non-dialogue) sentence.

It is sometimes used on its own (usually in speech bubbles in cartoons, comics) for comedic effect, to represent speechlessness or bewilderment.

Mathematical

Mathmatics often uses the ellipsis in examples, often example ranges and structures, signaling there may be any amount of other entrues, for example n₁, n₂, ..., n_i.

When doing the same in two-dimensionl matrices, you would use variations like the vertical (?, U+22EE (⋮)), diagonal (?, U+22F1 (⋱)) (and sometimes ?, U+22F0 (⋰)), and midline (raised) horizontal ellipsis (?, U+22EF (⋯)).