An overview of Esperanto’s gender neutral and non-binary grammar
Pronouns
Standard Esperanto features three third-person singular pronouns: “li”, corresponding to English “he”, “ŝi” corresponding to “she”, and “ĝi” corresponding to the English “it”. Some nonbinary Esperanto speakers may decide to simply use binary forms – either the same as their gender assigned at birth or the opposite. That doesn't make them any less nonbinary! Pronouns ≠ gender. The latter pronoun, similarly to its English equivalent, is considered by many not to be fit for referring to people, although some nonbinary people do use it anyway.
The standard pronoun “tiu” is proposed as a possible alternative to the binary “li” and “ŝi” and the not-personal “ĝi”, as it can simply mean “this person”. However, it is a correlative and not actually a personal pronoun.
The leading nonstandard pronoun is the neutral “ri”, which gained a lot of attention, especially among young speakers online. It is used as the default non-binary pronoun as well as simply the default pronoun by some, a role that was previously held by “li”. “Ri” is used as the default pronoun also on this very website.
Other nonstandard pronouns are: “ŝli” (created to be neutral, although rather in a binary way – as it is a short way of writing “he or she”), “gi” (a neutral pronoun being the personal version of “ĝi”), and “hi” (intended to be the masculine pronoun so “li” can become the neutral one). Unlike “ri”, these pronouns did not really come into frequent use.
Affixes
Esperanto does not have grammatical genders like those in Spanish. However, words describing people can be gendered. For example, “actor” is “aktoro” and “actress” is “aktorino”. Initially, such words were masculine by default, so “aktoro” meant a male actor and the feminine suffix “-in-” was necessary if one meant a female one. As time went by, most of these words became gender neutral. The ones that didn’t are usually related to family, “patro” is “father” and “patrino” is “mother”. There are also diminutive forms: “daddy” is “paĉjo” and “mommy” is “panjo”. Another important gendered nouns are “viro” – “man”, “virino” – “woman”, “knabo” – “boy” and “knabino” – girl.
In standard Esperanto, the prefix "ge-” can make a plural word have a meaning “…of both genders”. For example, “gepatroj” means “parents”, either a mother and a father or all parents of all the kids in the class. It is also sometimes used with already gender neutral words to highlight that both/all genders are meant; for example in the word “geesperantistoj” – “esperantists”, although this is rather rare. Recently people started using “ge-” for singular words, making them gender neutral. For example “gepatro” means a parent of any gender. Despite “amiko” (friend) being considered gender neutral, it is advisable to use “gekoramiko” for a romantic partner as “koramiko” may still be understood as “boyfriend”.
“-iĉ-” is a non-standard but recently popular masculine suffix that works like “-in-”. In an ideal word, “patriĉo” would mean “father” and “patro” could mean “parent”, however, users of “-iĉ-” know that they would be misunderstood if they started using words like “patro” as neutral today. The intention behind “-iĉ-” is to prevent masculine from being default in the language. When “man” is “viriĉo”, “virino” doesn’t sounds like just an addition to man. Some, inclduing Pronomejo.net go further and avoid the words “viro” and “virino” altogether using “uliĉo” and “ulino” instead (although these do not determine maturity). The suffix “-iĉ-” is not only for people, “bull” can be “boviĉo” instead of “virbovo”. “-iĉ-” is not random, it is based on the diminutive masculine suffix “-ĉj-” in analogy to “-in-” sharing the letter “n” with “-nj-”.
“-ip-” is a non-standard non-binary suffix. It is used the same way as “-in-” and “-iĉ-” but for people who don’t identify either as a man or a woman. So “patripo” is a non-binary parent and “amikipo” is a non-binary friend. Mind that it is NOT a gender neutral suffix. Just like “-in-” has “-njo” and “-iĉ-” has “-ĉj-”, there is a non-binary diminutive suffix “-pj-”. So “papjo” is a non-binary version of daddy/mommy. Diminutive suffixes can be also applied to names, so an Alekso can be called “Alepjo” (there are no strict rules where to cut the name).
There’s masculine “-ĉj-”, feminine “-nj-”, non-binary “-pj-” and there is also a non-standard gender neutral diminutive suffix “-j-”, although it is less common then the non-standard features above. Regardless, “pajo” can be a gender neutral way of saying mommy/daddy and a person named Riko can be called Rikjo or Rijo if they wish so.