|Spoken in:||many countries of Earth|
|Timeline/Universe:||international auxiliary language|
|Genealogical classification:||A posteriori
|Basic word order:||SVO|
|an Esperanto reform group||1907|
Comparison with Esperanto
Ido inherits many features of the grammar of Esperanto, and in many cases, the vocabulary is similar. Ido shares with Esperanto the goals of grammatical simplicity and consistency, ease of learning, and the use of loanwords from various European languages. The two languages, to a great extent, are mutually intelligible. However, certain changes were introduced to address some of the concerns that had arisen about Esperanto. These include:
- Esperanto's alphabet uses six non-Latin letters, three of which are not found in any other existing language; as a result, Esperanto in typing and in Internet e-mail and newsgroups frequently resorts to any of several schemes to represent these special letters. This leads to the situation where the same word may be displayed any of several different ways. Ido addresses this issue by using the 26-letter Latin alphabet with two digraphs, ch (/t͡ʃ/) and sh (/ʃ/) instead of Esperanto's ĉ and ŝ. The digraph qu, representing /kw/, as in English "quick", is used instead of Esperanto kv, and likewise gu is used instead of gv. Ido orthography is phonemic in the sense that each written word has an unambiguous pronunciation, but it does not have the one-to-one correspondence between letters and phonemes that Esperanto has.
- Ido generally does not impose rules of grammatical agreement between grammatical categories within a sentence, believing them to be grammatically complex and redundant in a potential universal second language. For example, in Esperanto, the verb in a sentence is invariable regardless of the number and person of the subject. This principle was not extended in Esperanto to adjectives and nouns; however, as a result, in Esperanto an adjective must agree in number and case with the noun it modifies as with the French grands livres (large books), where the adjective must be pluralized as well as the noun. There is no such requirement in English; for example, where number is emphasized by variation of the verb, and Ido eliminates this feature from its grammar.
- Esperanto requires the use of the -n ending to signify the use of the accusative case. Ido allows the use of this feature in ambiguous situations where the object of a sentence does not follow the subject, but in all other situations, the accusative case was eliminated as redundant.
- Ido imposes consistent rules on the use of endings to transform a word from one meaning or part of speech to another, thus simplifying the amount of vocabulary memorization that is necessary.
- Ido, unlike Esperanto, does not assume the male sex as the default for family relationship words. For example, Ido does not derive the word for "sister" by adding a feminine suffix to the word for "brother", as standard Esperanto does. Instead, some relationship root words are defined as sex neutral, and two different suffixes derive masculine- and feminine-specific words from the root—frato (sibling) > fratulo (brother), fratino (sister). In other cases, Ido has two or three root words where Esperanto has one—genitoro (parent), patro (father), matro (mother).
- Ido's vocabulary attempts to use cognates that are shared in common by as many of its six source languages as possible.
Nevertheless, modern Esperanto has received some influence from Ido in areas such as a clarification of the rules for word derivation and suffixes like -oz- ("abundant in") and -end- ("required to").
Ido has the common five vowels /a e i o u/.
The accent rule in Ido is regular, but slightly more complex than that of Esperanto: all polysyllables are stressed on the penultimate (next to last) syllable except for verb infinitives, which are stressed on the ultimate syllable—skolo, kafeo and lernas for "school", "coffee" and "learn", but irar, savar and drinkar for "to go", "to know" and "to drink". If an i or u precedes another vowel, the pair is considered part of the same syllable when applying the accent rule—thus radio, familio and manuo for "radio", "family" and "hand".