Using This Dictionary

inclusion policy

This dictionary is meant to include the core vocabulary of English-language science fiction; it also aims to cover several closely related fields, such as critical terms relating to science fiction and other genres of imaginative fiction such as fantasy and horror, or the vocabulary of science-fiction fandom. Words may be included because they arose in SF (even if they later became used in a more general way) or because they have a specific science-fictional use.

The goal is not to include every example of a word that appears distinctively in a SF source, however: idiosyncratic uses, or ones restricted to a particular author or universe, will generally not be put in. For example, Wikipedia includes 60 sentient species in the Star Wars franchise—in a list that only covers the letters A–E. The utility of including such terms in this dictionary would be rather limited, and we hope that most readers will at least agree that very few of these could be considered to be part of the ‘core vocabulary of science fiction’. Words used only in some narrow context can be entered if they are, nonetheless, known outside of that context.

Thus, waldo was coined by Robert Heinlein, but it is widely used by other writers; likewise Ursula Le Guin’s ansible. The word psychohistory is used chiefly by Isaac Asimov, but he uses it in a wide range of works, and it is often discussed by other writers, even though they refer to it as an Asimovian term. Similarly, J. R. R. Tolkien’s primary world and sub-creation are used frequently by later critics.

On the other hand, many words, even ones that are prominently used by well-known writers, remain limited to where they appeared. Examples include frelk, from Samuel Delany’s ‘Aye, and Gomorrah’; eptification, from John Brunner’s Stand on Zanzibar; orogene from N. K. Jemisin’s Broken Earth trilogy; and a number of Kurt Vonnegutisms, including ice nine and the terms connected to Bokononism in Cat’s Cradle. These will generally not be included.

Certain rare terms may be entered, usually because they are historically interesting, are semantically related to more common terms, complete a set of grammatically related forms, or for similar reasons.

Genuine scientific terms are a difficult issue. Words that were first used in SF (and continued to be used in SF), or that are used in SF in a notably different way from the scientific use, are all potential candidates for inclusion. Words that have always been scientific terms and that happen to be used in SF in the same sense are not generally entered; these do not become science-fictional solely because they are scientific. There are, however, some such terms that seem to give a science-fictional ‘flavor’ to a story, and we have occasionally put these in. But of all categories, the inclusion decisions around scientific terms are the most ambiguous.

This dictionary does maintain an internal list of potential entries; this list is fairly extensive, and it includes many items that could be included with more editorial time to research and write entries, as well as many items that are unlikely to ever meet the criteria for inclusion.

headword, part of speech, and sense numbers

The headword, or the ‘dictionary form’, is the basic form of a word: the singular form of a noun, the uninflected form of a verb. This dictionary uses the most common spelling for the headword, and it typically does not list variants separately. British forms of words are given preference, for example time traveller rather than time traveler. The different ways compounds can appear—written as two separate words, as one hyphenated word, or as one unhyphenated word—are rarely mentioned.

The order of headwords is strictly alphabetical, with spaces, punctuation, and capitalization ignored. For identically spelled headwords, the order of the parts of speech is: n., adj., adv., v., prefix, suffix, infix. Each sense of a word appears as its own separate entry; the senses are given sense numbers and are ordered strictly chronologically by the date of the first quotation. These numbers can change as the evidence changes—a newly drafted sense that is earlier than existing senses will cause a renumbering, as would an earlier quotation discovered for the second of two existing senses—so the sense number cannot be used as a stable reference for a particular sense.

The parts of speech are used in the usual manner of identifying English grammatical forms. Nouns used attributively, that is, to modify other nouns (as television in television screen) are not necessarily classified as adjectives; however, if there is a separate adjectival entry, such words will appear there. Verbs are not normally labelled for transitivity (that is, whether they take an object); their use will be clear from the definition and the quotations.


Definitions are intended to be comprehensive but brief; a dictionary is not an encyclopedia. The definition should cover the basic use of a word, but it does not usually aim to capture all the nuances of how it can be used; the quotations can provide a clearer picture of this. In this dictionary, definitions appear as fragments rather than full sentences; additional similar meanings may be combined with words like ‘hence’ or ‘also’, and in general, similar meanings are grouped together rather than expanded into separate entries. After the definition proper, additional discussion may be given, including usage or frequency labels, variant forms, historical information, links to more thorough discussion, etc.; this is treated as a discursive section, with regular punctuation.


Some words will have an etymology, which appears in square brackets after the definition. Etymologies are only provided when the origin is not simply an obvious shift in meaning of a regular word.

subjects and other links

Words may be given any number of subject labels; these are linked to a subject page, which includes a brief description of the category and a listing of all entries in that category. Words may also be linked to other sources, such as the Encyclopedia of Science Fiction, the Fancyclopedia, or Wikipedia.


The quotations are the most important part of this dictionary. In historical dictionaries, quotations demonstrate the history of a word by showing exactly how it was used. Many of the quotations in this dictionary were originally taken from a database collected for the Oxford English Dictionary. Some were gathered by one of the OED’s regular reading programmes—general efforts to read a variety of sources and select interesting examples—while many others were found as part of a targeted effort by the original version of this project. Since then, many quotations have been removed (the original group was an automatic export of the OED database, and many quotations were in the wrong place, and many were superfluous), and many more have been added.

A quotation that does not represent an example of the word being defined is placed in square brackets. Typical reasons for this are a different form or part of speech, a related sense that is not worth including on its own but sheds light on the use in question, or a description of a technical process that does not use the word itself. Bracketed quotations typically appear only as the first quotations; the need to include non-representative examples is smaller, once the evidence grows.

The date given for a quotation is the date when a work was published, or in some cases, was known to be written. An author's name in small caps is the person responsible for the use of the word; names that appear in regular type typically indicate an editor of a volume who did not write the quotation in question. Pseudonymous authors are given in single quotation marks; this indicates the name used for the publication of a work, even if the author's actual identity is known. Thus, ‘Anson MacDonald’ was a pseudonym used by Robert Heinlein; stories published under that name will be attributed to ‘A. MacDonald’. Links to the author page, however, are based on the author's actual identity, so quotations from ‘MacDonald’ are linked to Heinlein’s page. Author’s first initials are usually abbreviated. Following OED standards, even regular pseudonyms, for authors known exclusively by that pseudonym, are also given in single quotes: Murray Leinster (real name William Fitzgerald Jenkins), C. J. Cherryh (real name C. J. Cherry), and Lester del Rey (real name Leonard Knapp) all have their usual names treated as pseudonyms.

Titles of works are typically abbreviated; works like a/an and the are often omitted. A title given is the title of the version we are excerpting, even if the title has been changed for other editions. When works appear in multi-author or multi-work collections, the word in separates the information of the work from the information about the collection itself: A. N. Author Title in Periodical Name. If a work has multiple columns, the column number appears after the page, separated by a slash; the column number only counts text columns, not advertisements. The page and column number represent the place where the word being defined actually appears, not to where the extract starts.

The text of a quotation is the text as it appeared when published. A small number of stylistic changes have been made: quotation marks have been regularized, for example. Material omitted from within a quotation is indicated by ellipses, but we will silently uppercase the start of a quotation if it is taken from within a sentence, and we will not indicate a quotation that has been ended before the end of a sentence. That is, all quotations begin with a capital and end with closing punctuation. The goal has been to provide enough evidence to see the meaning of the word being defined, but not so much as to be overwhelming. In some cases, the style or even the meaning of a passage may have been changed by the way quotes have been extracted from their original context.

selection of quotations

The goal of a quotation section is to find the earliest quotation possible, show a range of evidence throughout a word’s use, and end with a (relatively) recent example. Quotations should show as wide a range of usage as possible: different authors, different publications, different styles, different grammatical patterns, different nuances. They should be interesting to read on their own. Needless to say, it is impossible to produce an individual quotation section that fulfills all of these requirements.

It is neither practical nor helpful to include a very large number of quotations; this ends up being overwhelming for the reader. For well-established older words, the OED might only include one example per century; newer terms might have one per decade. Dictionaries that focus on newer words, or ones that are online, effectively having no limits on space, can include more evidence, but showing more than (say) two dozen examples is probably a sign that the entry needs to be split up. The number of quotations does not correspond to the frequency of a term; while an extremely rare word might only have two or three examples because there aren’t any more, a very common term will not have this frequency reflected in the choice of quotations.

The goal of most dictionaries is to show typical use; unusual examples, while perhaps more ‘interesting’, generally do not belong in. Just as one would not read postmodern poetry to learn English as a second language, so too should a dictionary not seek to focus on outlying examples. As a result, dictionaries tend to privilege a certain type of writing. For this dictionary, works of hard science fiction, focused on the scientific details, are more likely to generate widely used terms than less technical stories. Thus, the reason this dictionary includes relatively few quotations from such authors as, say, Octavia Butler, Neil Gaiman, N.K. Jemisin, or China Miéville is not from the personal preference of the editor (who is extremely fond of these writers) but because their styles are more idiosyncratic and do not use as much of the shared vocabulary of SF.

quotation links

Each quotation may have up to three links:

  • Page images: Where possible, we link to images of the original source of a quotation. The overwhelming majority of such links are to the Internet Archive, whose comprehensive collection of SF pulps has been an indispensable source. Additional sources include the Fanac Fan History Project, which has a large number of fanzines, and to the Hathi Trust.
  • Author page: A page on this site that includes all quotations from that author, as well as links to other sources of information about that author. Authors are identified based on their ISFDB information. Not all authors have been tagged yet.
  • Bibliography: A direct link to the ISFDB title entry (not publication entry) for the work. Many works remain untagged. There are currently no internal links (that is, within this dictionary) to works.

research details

The information in the Research Details section relates to the actual research of the entry. The Research Requirements shows the date we’re considering (almost always the date of the first quotation) and the kind of example we’d like to find. This will usually be an antedating, that is, a verifiable example of a term earlier than we currently have; other possibilities are an interdating (filling a gap in the evidence), a postdating (a later example than the latest we have), and any evidence. The Earliest Cite is a short description of the earliest example we have.

The Research History gives a breakdown of the research that has been conducted on the entry. In particular, it features a detailed listing of what quotations have been sent in by which volunteer researchers. In most cases, this does not represent the actual quotation sections: the quotation section is not meant to be exhaustive; many quotations that were sent in are not shown on the site, and additional evidence often comes from sources outside of the original project. Also, quotations added by Jesse Sheidlower are not typically indicated.

In the original incarnation of this project, the Research Details was highlighted: it was the fundamental purpose of the entire endeavor. With the inclusion of the quotations, it became less necessary, as readers could glean what they needed to do by looking at the entry itself. While it will never be eliminated—credit for the contributors is crucial—it has now been moved to the bottom. However, the information here is continuously updated and still represents the current state of research.