By way of introduction, this question is about a quirk of Esperanto, but there is a general conlang question at the end, I promise.

In Esperanto, every root has a natural grammatical part of speech, much like how nouns have a grammatical "gender" (or noun category) in many other languages.

For example, "ŝoveli" means "to shovel". It is naturally a verb. The same root with a noun ending, "ŝovelo", does not mean "a shovel". Rather, it is the noun-of-the-verb, that is, it refers to the act of shovelling. To refer to a shovel, you have to say that it's the tool of the act of shovelling, that is, "ŝovelilo".

Similarly, "humana" means "humane". It is naturally an adjective. The same root with a noun ending, "humano", does not mean "human", it is the noun-of-the-adjective, that is, "humaneness".

This was an interesting design choice, and one that's puzzled me. For an Esperanto speaker, this is something you have to learn about every root, like noun classes in many IE languages.

Are there any analogues to this in natural languages, or is this a device that has been used in other conlangs?

  • 1
    If you are referring to a noun behind an adjective/adverb, I would say that in Italian normally there is always a substantive behind them that shares the same root (e.g. bello*/*bellezza, beauty*/*beautiful). The substantive could be collective/abstract, but still is a substantive. (Notice also that bello is used as adjective and substantive, so I can say il bello dell'aula to mean the most beautiful person of the classroom (which could also be sarcastic).
    – apaderno
    Feb 7, 2018 at 6:16
  • 2
    As for natural grammatical part of speech, I would say that grammatical parts of speech aren't natural, but concepts introduced from grammar when studying languages and their similarities.
    – apaderno
    Feb 7, 2018 at 6:16
  • That's a very good point.
    – Pseudonym
    Feb 8, 2018 at 1:34
  • I'd rather say it is a quirk of English that roots and even complete words don't have an assigned part of speech and that you can verb a noun and noun a verb without applying any derivational morphology. In inflecting or agglutinating languages part of speech is pretty overt by the affixes a word carries and changing the part of speech can only be done by derivation. It is also quite normal that a root is either verbal or nominal.
    – Sir Cornflakes
    Feb 10, 2018 at 19:19
  • For the case of Esperanto, see also this question in Esperanto Language: esperanto.stackexchange.com/questions/2785/…
    – Sir Cornflakes
    Feb 16, 2018 at 17:38

2 Answers 2


This is pretty common in natural languages. Think about English words -- most of them have an inherent part of speech and require derivational affixes to change that. "Anger" is inherently a noun and requires "-y" to become an adjective, whereas "excite" is inherently a verb and requires "-ment" to become a noun or "-ed" or "-ing" to become an adjective. This sort of thing is incredibly normal in natlangs -- the reason it seems a bit abnormal in Esperanto is that Esperanto derivation is far more productive than even derivation-heavy natlangs, leading to irregularities in these sorts of changes being much more noticeable.

Also, as an aside, because "human-" is inherently adjectival, you would not say "humano" to mean "humane-ness", but "humaneco" (source). Adding the "-eco" suffix, meaning "the quality of" or something to that effect, is necessary for adjectival Esperanto roots. This is the very reason why Esperanto roots are said to have inherent part of speech, and it's a large part of why the "-eco" suffix exists in the first place.


Esperanto roots principally can basically form nouns/adjectives/adverbs and adverbs (and are not words themselves):


  • -o noun
  • -a adjective
  • -e adverb
  • -i verb, infinitive

Roots and derived words:

  • naci- "nation" - 'noun' root

    • nacio = nation
    • nacia = national
    • nacie = nationally
    • naciigi = nationalize, suffix -ig' = make ~
  • pens- "thought" - 'verbal' root

    • penso = thought
    • pensema = thoughtful, suffix -em' = inclined to ~
    • pensi = think
    • pensado = thinking (the ~, noun), suffix -ad' = act of (repeated) ~ing
  • hom- "human men/women" - 'noun' root

    • homo = human being
    • homa vivo = human life
    • homaro = humanity, -ar' = collection, the collection of humans
  • human- = humane - 'adjective'

    • humanisto = humanist, -ist'
    • humaneco = humanism, the quality of being humane, -ec' = ~ity
    • humanismo = humanism, the philosophical movement

So actually the endings do not always guarantee a meaningful word, and the same for suffixes. Suffixes come into play. The hard thing is to know whether the root refers to a noun/adjective/verb. And for a verb whether it is transitive or intransitive.

Weird in Esperanto is that the root itself is not used; say as noun/adjective/verb. It consistently requires an ending, despite the root often having an identifiable category. National languages have the same usage problems (roots not being flexed to every category), but do not have this redundancy of endings. For that they have ad-hoc pseudo-suffixes like -al and -ive.

One might argue that Chinese and English often do not make a distinction between parts of speech. The English success can either be noun or verb. However Esperanto was made similar to the European languages but clear.

Note for a conlang one cannot simply drop then noun ending and assume every root to be a noun. You would then have to determine whether always a noun is present.

The exceptions to non-standalone roots are prepositions, numbers and such.

  • kun = with, in company of; a word, "preposition"

    • kuna = common, communal
    • kune = together
    • kuniĝi = come together, -iĝ' = become
  • tri = three, a word

    • trio = trio, group of three
    • tria = third
    • trie = thirdly
    • trioblo = threefold, -obl' = multiple
    • triono = a third 1/3, -on' = fraction
    • triope = by three, in threes, -op' = group of ~

Sorry if this answer is a bit Esperanto heavy, but a conlang might benefit from this nice system. How about just -a for nouns: scola, biblioteca, bulgaria?

  • 1
    Not using the root itself isn't that weird: in essence, it's similar to a Semitic root system where the root itself isn't used (and usually isn't even pronounceable) and requires additional vowels and consonants in order to determine its parts of speech and defintiion. The standard example is the root K-T-B, which means the concept of writing. Kitab (book), naktub (we write), maktabat (library/bookshop), and so on. Jan 23, 2020 at 17:50

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