Novial is a constructed language invented by Otto Jespersen (who had previously been part of the group that created Ido) and first published in 1928. Jespersen had come to dislike some aspects of Ido, and wanted to create a language that was more naturalistic and irregular. After Jespersen’s death in 1943 the language basically went dormant, and although the Internet revived some curiosity in it, if I’m not mistaken there are basically no Novial speakers today.
Like Ido, Novial’s vocabulary is primarily Romance and partially Germanic. Novial’s grammar, though, was largely based on English. (English grammar was Jespersen’s field of expertise as a professional linguist.) Novial has considerably more verbal complexity than Ido, but uses auxiliary verbs to express those shades of meaning rather than verb endings (with the exception that you can use -d for the simple past).
Another difference between Novial and Ido is that Novial ditched the word endings showing word class (like -o for nouns, -a for adjectives, etc.) that Ido had inherited from Esperanto. Word endings still have meanings, they’re just more narrow than that (and the same ending can have multiple meanings). For example:
- for nouns referring to living beings, -e is the gender-neutral ending, -o is masculine, and -a is feminine. You can also just not have any ending, and then the noun is of indeterminate number. (e.g. Leon es kruel = “Lions are/the lion is cruel.”)
- if a noun is based on an adjective, you can use the endings above for words for living beings based on that adjective, and there is also -u for concrete objects and -um for abstract concepts.
- if a noun is based on “a tool or means”, the word ending in -e refers to the tool or means itself, -a is the verb describing usage of that tool, and -o is the noun referring to the act of using the tool.
The plural is formed by adding -s (-es after a consonant). Adjectives end in -i, but you can drop it. (Indeed with adjectives formed with some endings, like -an and -al, it seems virtually compulsory to drop the -i.) Adverbs are formed by adding -m to the form of the adjective ending in -i. There is no specific ending for verbs, but suffixes that turn other types of words into verbs generally end in -a.
The accusative marker is not compulsory but may be used; it’s -m, or -em after a consonant. There is also a genitive marker (cf. English ’s), -n, or -en after a consonant. These markers go after the plural ending if there is one.
Novial retains (sometimes in slightly-changed form) most of the affixes from Ido. A few have been replaced. For example, the intensifier -eg- is replaced with -isi (cf. Romance forms like -ísimo, -issimo, -íssim). The ending -em-, meaning “tendency towards”, is replaced with -asi. And affixes like -ey- and -eri- meaning “place of” have been replaced with -torie. It seems to me, though, that the affixes are not really used with the same vigour as in Esperanto or even Ido, but more as a way to justify how borrowings from European languages (like internacional or observatorie) were related to their root words.