# Esperanto slang and in-group words: krokodili, kabei, mojosa

Source: https://esperantopedia.org/phrases/esperanto-slang/
Language: en
Updated: 2026-10-11

> Esperanto slang explained: krokodili (speaking another language), kabei (quitting, after Kabe in 1911), mojosa (cool, coined 2003), gufujo and more.

Esperanto slang is the informal vocabulary that speakers made for themselves: ***krokodili*** "to speak another language among Esperantists", ***kabei*** "to quit the movement", ***samideano*** "fellow Esperantist" and ***mojosa*** "cool". Courses rarely teach these words, but you will meet them at congresses, in groups and in chat. Most are built from regular word parts such as *-ul-*, *-ism-* and *-aĵ-* (see [suffixes](https://esperantopedia.org/grammar/suffixes/)), so you can often guess them. Pronunciation guides show the stressed syllable in capitals.

## Words for the community

| Esperanto | Meaning | Origin / note |
|---|---|---|
| *Esperantujo* (es-pe-ran-TU-jo) | the "land" of Esperanto: the community and every place it meets, from congresses to online groups | *Esperanto* + *-ujo*, as in country names (*Francujo*). Also written *Esperantio*. It has no territory. |
| *samideano* (sa-mi-de-A-no) | fellow Esperantist; a friendly way to address one | *sama* "same" + *ideo* "idea" + *-ano* "member". Zamenhof used it in congress speeches. |
| *esperantisto* (es-pe-ran-TIS-to) | someone who knows and uses Esperanto | Some prefer *esperantoparolanto* "Esperanto speaker", because *-isto* can suggest a profession or ideology. |
| *verdulo* (ver-DU-lo) | a keen Esperantist | *verda* "green" + *-ulo* "person"; green is the movement's colour. It also means a member of a Green party. |
| *denaskulo* (de-nas-KU-lo) | native speaker: someone who learned Esperanto as a child at home | *denaska* "from birth" + *-ulo*. See [native speakers](https://esperantopedia.org/about/native-speakers/). |
| *interna ideo* (in-TER-na i-DE-o) | "inner idea": the hope that Esperanto will bring peoples closer like brothers | Zamenhof's phrase, used in speeches, for example at the Kraków congress in 1912. |

## Words about using the language

| Esperanto | Meaning | Origin / note |
|---|---|---|
| *krokodili* (kro-ko-DI-li) | to speak a language other than Esperanto among Esperantists, usually your shared native one | *krokodilo* "crocodile" + *-i*. The origin is uncertain; one story is a wooden crocodile in Andreo Cseh's classes. |
| *aligatori*, *kajmani*, *gaviali* | rarer cousins. *Aligatori*: another language that only some present speak natively. *Kajmani*: one that nobody present speaks natively. *Gaviali*: using Esperanto where another language would suit better | More reptiles, copying *krokodili*. The exact definitions vary. |
| *kabei* (ka-BE-i) | to leave the Esperanto movement after having been active in it | From the pen name *Kabe* of Kazimierz Bein; see below. |
| *volapukaĵo* (vo-la-pu-KA-ĵo) | gibberish; something you cannot understand | *Volapuko* + *-aĵo* "thing". A joke about Volapük, an earlier planned language (1879) that competed with Esperanto. |
| *bonantagulo* (bo-nan-ta-GU-lo) | teasing word for someone whose Esperanto is only a few greetings | *bonan tagon* + *-ulo*. It can sound unkind, so use it carefully. |
| *mojosa* (mo-JO-sa) | cool, great, stylish; mostly heard from younger speakers | Made up in 2003 at a youth seminar in Hungary from the first letters of *modern-jun-stil* "modern-young-style": M, J, S, spoken *mo-jo-so*. Also *mojosega* "very cool". |

## Words about the movement's goals

| Esperanto | Meaning | Origin / note |
|---|---|---|
| *fina venko* (FI-na VEN-ko) | "final victory": the hope that one day most people will speak Esperanto as a second language | Often written *Fina Venko*. |
| *finvenkismo*, *finvenkisto* (fin-ven-KIS-mo, fin-ven-KIS-to) | working towards that goal; a person who holds this aim | *fina venko* + *-ismo* "doctrine" or *-isto*. |
| *raŭmismo* (raŭ-MIS-mo) | the view that Esperanto is valuable now, as a living language and cultural community, not only as a future world language | From the Rauma Manifesto, written in 1980 in Rauma, Finland. Often set against *finvenkismo*; see [criticism](https://esperantopedia.org/about/criticism/). |
| *zamenhofa* (za-men-HO-fa) | of Zamenhof; in line with his own usage and examples | PMEG calls the examples it takes from his texts *zamenhofaj*. |

## Events and places

| Esperanto | Meaning | Origin / note |
|---|---|---|
| *gufujo* (gu-FU-jo) | a quiet night café at Esperanto events: candles, tea instead of alcohol, no smoking, music or readings | *gufo* "(eagle-)owl", for night owls, + *-ujo*. First held at the end of 1995 at a German youth New Year seminar. |
| *UK* (u-KO) | the World Esperanto Congress, *Universala Kongreso* | See [World Esperanto Congress](https://esperantopedia.org/about/world-congress/). |
| *IJK* | the International Youth Congress, *Internacia Junulara Kongreso* | Held by TEJO; the first was in 1938 in Groet, Netherlands. |
| *Pasporta Servo* (pas-POR-ta SER-vo) | "Passport Service": a list of hosts who offer free beds to Esperanto-speaking travellers | Since 1974, with 40 hosts at first. See [Pasporta Servo](https://esperantopedia.org/about/pasporta-servo/). |

## Abbreviations in writing and chat

| Esperanto | Meaning | Origin / note |
|---|---|---|
| *ktp*, *k.t.p.* | "and so on" | *kaj tiel plu*. PMEG writes it with dots. |
| *ekz.* | "for example" | *ekzemple*. |
| *k.a.*, *k.s.* | "and others", "and similar" | *kaj aliaj*, *kaj similaj*. |
| *t.e.* | "that is" | *tio estas*. |
| *bv*, *bv.* | "please" | *bonvolu*, in messages and chat. |
| *s-ro*, *s-ino*, *d-ro* | "Mr", "Ms", "Dr" | *sinjoro*, *sinjorino*, *doktoro*. |

Casual greetings such as *Sal!*, *Ĉaŭ!* and *Ĝis!* are in [greetings](https://esperantopedia.org/phrases/greetings/). Keyboards without *ĉ ĝ ĥ ĵ ŝ ŭ* are why chats often type *cx*, *gx* and so on; see the [x-system](https://esperantopedia.org/learn/alphabet/).

## Who was Kabe, and why did his name become a verb?

*Kabe* was the pen name of Kazimierz Bein (1872–1959), a Polish eye doctor and a leading early Esperanto translator and stylist. The name is the Polish way of saying his initials, K.B. He took up the language in 1903, became famous in 1904 for translating Sieroszewski's novel *La fundo de l' mizero*, and was vice-president of the Academy of Esperanto from 1906. His translation of Prus's *La Faraono* followed in 1907.

In 1911 he left the movement suddenly, without explaining why. In a 1931 interview he said that the language's lack of progress meant he no longer saw it as the answer. Esperantists made *kabei* from his name, and by 1935 the poet Kálmán Kalocsay wrote, in the *Enciklopedio de Esperanto*, that it had become a symbol of apostasy.

## The slang in sentences

| Esperanto | English |
|---|---|
| *Ni krokodilis la tutan vesperon.* | We spoke our own language all evening. |
| *La koncerto estis mojosega!* | The concert was really cool! |
| *Tiu instrukcio estas por mi volapukaĵo.* | That instruction is gibberish to me. |
| *Ni renkontiĝu en la gufujo post la koncerto.* | Let's meet in the gufujo after the concert. |
| *Ĝis, samideanoj!* | See you, fellow Esperantists! |

## When should you use this slang?

- **Among friends, at events and in chat.** In formal writing, prefer standard words and the [basic phrases](https://esperantopedia.org/phrases/basic/).
- **Explain the word if unsure.** Many older speakers have never met *mojosa*.
- **Don't police others.** Vikipedio notes that scolding beginners with *Ne krokodilu!* can drive them away. Briefly switching language to explain a grammar point to a beginner is more accepted.

## Common questions

### What does krokodili mean in Esperanto?

It means speaking a language other than Esperanto among Esperantists, usually your shared native language. Speakers discourage it because events are a rare chance to practise, and it can leave others out and give outsiders a poor impression.

### What does kabei mean?

*Kabei* means to leave the Esperanto movement after having been an active member. It comes from *Kabe*, the pen name of Kazimierz Bein, a leading translator who quit in 1911.

### What does mojosa mean?

*Mojosa* means "cool". It was coined in 2003 from the first letters of *modernjunstila* "modern-young-style", and is now listed in the online dictionary ReVo.

### What is a gufujo?

A *gufujo* is a quiet, candle-lit night café at Esperanto events, with tea instead of alcohol. The first was held at the end of 1995; *gufo* means "owl".

### What is Esperantujo?

*Esperantujo* is the informal name for the Esperanto-speaking world, its community and meeting places, treated as if it were a country. It is also called *Esperantio*.

## Sources

- ReVo: [krokodili](https://reta-vortaro.de/revo/art/krokod.html), [Kabe, kabei](https://reta-vortaro.de/revo/art/kabe.html), [mojosa](https://reta-vortaro.de/revo/art/mojos.html), [samideano, interna ideo](https://reta-vortaro.de/revo/art/ide.html), [-uj (Esperantujo)](https://reta-vortaro.de/revo/art/uj.html), [verdulo](https://reta-vortaro.de/revo/art/verd.html), [denaskulo](https://reta-vortaro.de/revo/art/nask.html), [Fina Venko, finvenkismo](https://reta-vortaro.de/revo/art/venk.html), [raŭmismo](https://reta-vortaro.de/revo/art/rauxm.html), [Volapuko](https://reta-vortaro.de/revo/art/volapuk.html), [zamenhofa](https://reta-vortaro.de/revo/art/zamenhof.html), [gufo](https://reta-vortaro.de/revo/art/guf.html), [sinjoro](https://reta-vortaro.de/revo/art/sinjor.html), [doktoro](https://reta-vortaro.de/revo/art/doktor.html)
- PMEG: [UJ](https://bertilow.com/pmeg/vortfarado/afiksoj/sufiksoj/uj.html), [IST, ISM](https://bertilow.com/pmeg/vortfarado/afiksoj/sufiksoj/ist.html), [AĴ](https://bertilow.com/pmeg/vortfarado/afiksoj/sufiksoj/ajh.html), [UL](https://bertilow.com/pmeg/vortfarado/afiksoj/sufiksoj/ul.html), [AN](https://bertilow.com/pmeg/vortfarado/afiksoj/sufiksoj/an.html), [Simboloj kaj mallongigoj](https://bertilow.com/pmeg/aldonoj/simboloj_mallongigoj.html)
- Vikipedio: [Krokodili](https://eo.wikipedia.org/wiki/Krokodili), [Kabei](https://eo.wikipedia.org/wiki/Kabei), [Kazimierz Bein](https://eo.wikipedia.org/wiki/Kazimierz_Bein), [Samideano](https://eo.wikipedia.org/wiki/Samideano), [Gufujo](https://eo.wikipedia.org/wiki/Gufujo), [Mojosa](https://eo.wikipedia.org/wiki/Mojosa), [Fina Venko](https://eo.wikipedia.org/wiki/Fina_Venko), [Raŭmismo](https://eo.wikipedia.org/wiki/Ra%C5%ADmismo), [Interna ideo](https://eo.wikipedia.org/wiki/Interna_ideo), [Esperantistoj](https://eo.wikipedia.org/wiki/Esperantistoj), [Idiomaĵoj en Esperanto](https://eo.wikipedia.org/wiki/Idiomaĵoj_en_Esperanto), [Esperanta slango](https://eo.wikipedia.org/wiki/Esperanta_slango), [Internacia Seminario](https://eo.wikipedia.org/wiki/Internacia_Seminario), [Internacia Junulara Kongreso](https://eo.wikipedia.org/wiki/Internacia_Junulara_Kongreso), [Bv](https://eo.wikipedia.org/wiki/Bv)
- Wikipedia: [Kazimierz Bein](https://en.wikipedia.org/wiki/Kazimierz_Bein), [Esperanto culture](https://en.wikipedia.org/wiki/Esperanto_culture), [Esperantujo](https://en.wikipedia.org/wiki/Esperantujo)
- Wiktionary: [krokodili](https://en.wiktionary.org/wiki/krokodili), [kabei](https://en.wiktionary.org/wiki/kabei), [mojosa](https://en.wiktionary.org/wiki/mojosa), [mojosega](https://en.wiktionary.org/wiki/mojosega), [gufujo](https://en.wiktionary.org/wiki/gufujo), [samideano](https://en.wiktionary.org/wiki/samideano), [volapukaĵo](https://en.wiktionary.org/wiki/volapuka%C4%B5o), [bonantagulo](https://en.wiktionary.org/wiki/bonantagulo), [verdulo](https://en.wiktionary.org/wiki/verdulo), [denaskulo](https://en.wiktionary.org/wiki/denaskulo), [fina venko](https://en.wiktionary.org/wiki/fina_venko), [finvenkismo](https://en.wiktionary.org/wiki/finvenkismo), [interna ideo](https://en.wiktionary.org/wiki/interna_ideo), [ktp](https://en.wiktionary.org/wiki/ktp), [bv](https://en.wiktionary.org/wiki/bv), [s-ro](https://en.wiktionary.org/wiki/s-ro), [d-ro](https://en.wiktionary.org/wiki/d-ro)
- Felix Zesch (one of the coiners): [Mojosa](https://felicx.livejournal.com/79673.html)