esperantismo

This is the word the movement wrote a definition for, and the definition is the interesting part. Most -ismo words are named by their opponents. Esperantismo was defined by its own first world congress, in a document adopted at Boulogne-sur-Mer in August 1905 and known ever since as the Deklaracio pri Esperantismo, the Declaration of Boulogne. Its first point opens:

La Esperantismo estas penado disvastigi en la tuta mondo la uzadon de lingvo neŭtrale homa, kiu...

Esperantism is an effort to spread throughout the world the use of a neutrally human language. The sentence then runs on for another eighty words to say what that language does not do: it does not intrude into the internal life of peoples, it does not aim to push out any national language, and its business is letting people of different nations understand one another. The point ends by declaring that any further idea or hope an individual attaches to Esperantism is that person's private affair.

That last clause is the whole political settlement of the movement in one line. It is what allows a Catholic association and an atheist one to sit on the same UEA list; it is why a samideano can mean somebody who agrees with you about a language and about nothing else. Zamenhof himself had a great deal more in mind - the interna ideo, the inner idea, a project of human brotherhood the language was only the instrument for - and the Declaration is precisely the document that fenced that off as personal rather than official. The tension between the two has never been resolved and has never needed to be; the full account is in Esperantismo kaj la interna ideo, this chapter's own article.

And the Declaration did one more thing that still binds. Its fourth point named the Fundamento as the only obligatory authority over the language, which is why an argument about correct Esperanto still ends by opening a book from 1905 rather than by taking a vote.

Morphologically it is entirely ordinary. Esperanto plus -ism- plus -o, exactly as esperantisto is Esperanto plus -ist-. This is the real -ismo, the doctrine suffix doing doctrine work, which is worth noticing in a band that also contains organismo, where the same five letters are an accident of Greek spelling and mean nothing at all.

Register. Movement vocabulary, slightly formal, and dated in flavour - a speaker today is more likely to say la movado or Esperanto-kulturo. You will meet esperantismo in congress speeches, in histories, and in the Declaration itself. Esperantisma is the adjective.