Like natural languages, the constructed language Esperanto contains profane words and indecent vocabulary. Some of this was formulated out of the established core vocabulary, or by giving specific profane or indecent senses to regularly formed Esperanto words. Other instances represent informal neologisms that remain technically outside the defined vocabulary of the language, but have become established by usage.
Esperanto distinguishes between profanity and obscenity (this distinction is not always made in English). Profanity in Esperanto is called , after the older French , and consists of what English speakers would call "oaths": religious or impious references used as interjections, or to excoriate the subject of the speaker's anger. According to Renato Corsetti, former president of the World Esperanto Association, is "a word or phrase used to express one's indignation or anger or similar sentiment, not directly addressed to a particular person."
Obscenity in Esperanto is described as or ("indecent"), ("vulgar, indelicate, low-class"), ("taboo"), ("sharp, stinging") or ("ignoble"). These are the Esperanto words that refer to sexual acts and bodily functions in non-clinical ways.
Alos & Velkov (1991) use vocabulary along these lines, put into the "" (abbreviation) legend:
As a planned language designed for international communication neither interjections to be used in anger, expletives nor familiar expressions for sex acts and bodily functions were priorities for L. L. Zamenhof, and as such this sort of vocabulary does not loom large in either the Unua Libro nor in the Fundamento de Esperanto. According to Alos and Velkov, "neither Zamenhof nor the other pioneers of the international language used obscene words in their works; nevertheless, they all tried to make Esperanto a real language."
Alos and Velkov's remarks suggest a belief that a language without expletives or familiar expressions for sex acts and bodily functions is incomplete. Such a language would fail to respond to all of the situations that humans use language for. In furtherance of making Esperanto more "real" in this sense, Esperantists have created or invented the vocabulary thought to be missing. A number of important Esperantists have worked to further this effort.
In 1931, the poet Kálmán Kalocsay published ("Secret Sonnets"), a poem cycle on erotic themes, that helped circulate some of the unofficial root words that form part of the basis of familiar sexual expressions in Esperanto. In 1981, Hektor Alos and Kiril Velkov published a small pamphlet on ("Taboo words in Esperanto: a dictionary with examples for practical use") that also discussed Esperanto sexual expressions and oaths; their pamphlet was distributed by the major Esperanto language book services. In 1987, Renato Corsetti, who later became president of the World Esperanto Association, published ("Knead me, madam: taboo and insulting expressions in Esperanto"), that also discussed this aspect of Esperanto vocabulary, and increased its coverage of interjections and expletives. The title of Corsetti's book plays on that of Kredu Min, Sinjorino! ("Believe Me, Madam"), a well-received original novel in Esperanto by Cezaro Rossetti.
Some of the profane vocabulary of Esperanto is derived by giving specific and profane meanings to words formed according to the regular methods of Esperanto grammar. For example, one Esperanto word for "a female prostitute" is . This word, which has no direct cognate in any European language, is confected entirely from a priori elements belonging to Esperanto alone: a female () person () who "belongs to everyone" (). This last root is one of the systematically formed Esperanto correlatives. While the word could mean anything indicated by its constituent parts, usage has confined it to this particular sense. Since Esperanto grammar regularly allows the creation of new words, it lends itself to the generation of a large number of synonyms; as an example of the process, the words ("public person"), ("street person", compare English streetwalker) and ("self-seller") have all been coined to refer to prostitutes.
In addition to this formation, the word also means a female prostitute, from a widely distributed Romance root. Esperanto also has the formal verb , to prostitute.
Esperanto grammar allows and encourages the development of new vocabulary along these lines. The Esperanto word means "to have sexual intercourse" or, more generally, to engage in sexual activity; it combines the word for "gender" () with the indefinite kadigan suffix '; , "to masturbate", is a similar construction on the word for "finger" (), though the normal meaning of the word is "to feel/touch with the fingers"; and , to fellate, from , "tongue" as a body part. An oblique word for menstruation is , combining "month" with a suffix meaning roughly "matter".
Other Esperanto profanities are simply the Esperanto words that name subjects invoked as oaths. The devil () is frequently invoked in these, with phrases such as ("May the Devil take it!"), ("May the Devil eat you!") and ("What a piece of deviltry!")
The fundamental vocabulary of Esperanto contains a number of pejoratives. The root fuà Â- means "to botch" or "to bungle", and as such figures prominently in some of these formations; a is a FUBAR situation. ' also figures as a pejorative prefix. The prefix ' (roughly, "immoral") and the suffix ' (roughly, "bad, inferior") are also parts of the core vocabulary with pejorative functions; they have been combined to produce words such as , a thoroughly disgusting person. Fek- is the Esperanto root for dung; Alos and Velkov report encountering combinations like ("fuck-shit")
As in many natural languages, some medical/anatomical terms can be taboo or profane if used outside the medical context. A&V give examples such as (Sci), (Sci) or (Sci); or normal words like (GV) - to lubricate or menstruation, (GV).
Another source of Esperanto profanity is mock-sacrilegious terms, which are humorous oaths that refer to Esperanto culture. These uses are cultural references without any taboo connotation, but used as if they were profanities. The use of phrases like ("Acts of the Academy") and ("Fundamental Chrestomathy") invoke the names of Esperanto institutions and Dr. Zamenhof's books. A similar form of profanity in a natural language can be seen in Quebec French profanity.
As in American English or Russian, variations of stress from an affixed root to a suffixed root or vice versa may give the word another, profane meaning (international students' pun: an-alysis (calculus) to anal-lysis). Other forms of mincing to "profane" an everyday word or "de-fame" a profanity (like hellâÂÂheck in Puritan countries, or artistic: words like "frack" or "feldercarp" in Battlestar Galactica) are exchanging a consonant or vowel, or adding/omitting a circumflex (àto c or vice versa).
Other such words in Esperanto are technically "neologisms", words that were not added to the core vocabulary by Dr. Zamenhof, nor made official by the Esperanto Academy. Many of the items of the profane vocabulary do not appear in the official word list published by the Esperanto Academy. They appear, nevertheless, in standard reference works such as Gaston Waringhien's Plena Ilustrita Vortaro de Esperanto, often with the note that they are indecent neologisms.
In 1932, Kálmán Kalocsay (writing as "Peter Peneter") publicized, if he did not invent, much of the informal sexual vocabulary of Esperanto in his poem cycle ("Secret Sonnets"). The poems conclude with an appendix, also set forth in verse, that defines each of the neologisms found in the poems themselves, including Esperanto roots such as , "to fuck", borrowed from German; , "cock" in the sense of "penis", borrowed from Italian; and , "cunt", borrowed from Slavic. One of Kalocsay's poems consists of little more than a listing of synonyms for sexual intercourse generated by the combinatory possibilities or metaphorically extended meanings of Esperanto words:
Once a root achieves currency in Esperanto, it becomes available to all of the derivational processes of Esperanto grammar; so that "to fuck" is the source for , a dildo or a penis, literally a tool (-ilo) for fucking; and for many other regularly formed words.