Ido for Esperanto Speakers

Sometimes, you’ve already developed a strong base in one language but then you need to shift and learn another language that seems very similar, but has its own nuances. Sometimes it’s C++ to Java. Sometimes, it’s Esperanto to Ido.

This is my attempt at summarizing differences in grammar between Ido and Esperanto, for people who already have a meznivela understanding of Esperanto.



Ido alphabet (same as English alphabet):


Esperanto alphabet:


  • Instead of “ĉ” and “ŝ”, Ido uses “ch” and “sh”.
  • Instead of “ŭ”, Ido uses “w”.
  • Instead of “ks” / “kz” sound, Ido uses “x”.
  • The letters “ĝ” and “ĵ” are merged into the letter “j”.
  • “y” has the y-sound in Ido, where in Esperanto “J” sounds like a y-sound.

From Comparison between Esperanto and Ido, Phonology


With Esperanto, the stress always goes on the penultimate (second-to-last) syllable.

With Ido, the rules are:

  1. With words with multiple syllables, the second-to-last syllable is stressed. (kafeo, lernas)
    1. EXCEPT with infinitive verbs, then the last syllable is stressed. (lernar, drinkar)
  2. If an “i” or “u” is before another vowel, the pair is considered part of the same syllable. (?: Are these diphthongs?) (radio, familio)
    1. EXCEPT if the two vowels are the only vowels in the word, then the “i” or “u” is stressed. (dio, frua)

From Comparison between Esperanto and Ido, Phonology


Many suffixes are the same between Esperanto and Ido, save for the following:

Infinitive Suffix

  • Esperanto: -i (paroli)
  • Ido: -ar (parolar)

Additionally, in Ido there are past, present, and future infinitive tenses:  -ir, -ar, -os, respectively.

Imperative Suffix

  • Esperanto: -u (lernu)
  • Ido: -ez (lernez)


  • Esperanto: add -j after the -o (noun marker) and the corresponding -a (adjective marker). (belaj katoj)
  • Ido: replace the -o (noun marker) with -i. Adjective does not need to agree. (bela kati)

Object Marker

  • Esperanto: The object marker -n gets appended to the object of the sentence and its corresponding adjective.
  • Ido: The object marker is left off if the sentence is in subject-verb-object order. The -n can be added to clarify the object.

Cxu, kaj, aux, al

  • Cxu = ka, kad
  • Kaj = e, ed
  • Aux = o, od
  • Al = a, ad

With these words in Ido, you can drop the final d letter if the following letter (first letter in the next word) is also a consonant.

  • Ka vu vidas? / Kad ulu prizas kuko?
  • Me e vu. / Me ed elefanto.
  • Piano o violino? / Hike od ibe?
  • Me iros ad usa. / Me iros a la kafeerio.


The correlatives in Ido are not the same as in Esperanto, where you just memorize a beginning (what/that/some/any/none/every) and an ending (person/thing/place/etc.) separate and put ’em together.

PERSON qua/i (i)ta/i ulu/i irgu/i nulu/i omnu/i
THING quo/i (i)to/i ulo/i irgo/i nulo/i omno/i
PLACE ube ibe ulaloke irgaloke nulaloke omnaloke
TIME kande lore ulatempe irgatempe nulatempe sempre
WAY quale tale ule irge nule omne
QUANTITY quanto tanto ulaquanto irgaquanto nulaquanto omnaquanto

Table from A Quick Ido Grammar Reference

Nouns, Verbs, and Adjective Interchangeability

Ido reformed the interchangeability between root words and the noun, adjective, and verb suffixes in order to make it more logical and to make it reversible.

(* researching)


In the original Esperanto, masculinity was assumed for nouns. In modern days, simple nouns tend to be assumed to be neutral (except with family roles generally), but there can be discrepancy between older and younger Esperantists.

Also with Esperanto, there is a feminine -in suffix (“kato” = cat (neutral or masc.), “katino” = female cat), but no official corresponding masculine suffix (-iĉ is the common unofficial one, or one could use the prefix vir- to denote masculine, which creates asymmetry).

In Ido, no gender is assumed for root words – they are sex-neutral. There are two different suffixes for feminine and masculine.

  • Servisto – Waiter of either gender
  • Servistulo – Male waiter
  • Servistino – Female waiter

There are two exceptoins, where there are separate words rather than a common root:

  • Father: Patro, Mother: Matro, Genitoro: Parent
  • Viro: Man, Muliero: Woman, Adulto: Adult

From Comparison between Esperanto and Ido


Pronouns don’t all end with the same “i” in Ido, since it can be difficult to distinguish the sounds between them. There are also more pronouns in Ido than in Esperanto:

singular plural indefinite
first second third first second third
familiar formal masculine feminine neuter pan-gender masculine feminine neuter pan-gender
Ido me tu vu il(u) el(u) ol(u) lu ni vi ili eli oli li on(u)
English I thou/you you he she it he/she/it we you they one
Esperanto mi ci vi li ŝi ĝi ĝi¹ ni vi ili oni

From Comparison between Esperanto and Ido, Pronouns

“ol” is not limited to inanimate objects, and can be used for indeterminate gender.

See also