osion

Osion is not a standalone English word. It is the sequence of letters "osion" that appears at the end of a small number of nouns formed from verb stems through the Latin-derived suffix -sio(n). In linguistic discussion, osion is sometimes noted as a recognizable orthographic ending rather than as a morphologically productive unit in contemporary English.

Etymology and morphology: The suffix -sion (from Latin -sio, via Old French -sion) commonly creates nouns that denote action, process, or result. In English spelling, the ending can appear as -sion or -tion, and the letters osion occur specifically when the preceding letters contribute to the word’s final syllable. Words such as erosion and explosion end with the sequence -osion, illustrating how the stem combines with the -sion-type ending.

Examples and usage: The most familiar English words ending in osion are erosion and explosion. These illustrate the general pattern where a verb-derived stem combines with -sion to form a noun referring to a process (erosion) or a result (explosion). Osion itself is not a productive suffix in modern coinage; new words typically use the more common -sion or -tion endings. In analyses of spelling and historical orthography, osion is often discussed as a characteristic cluster found in certain -sion words rather than as an independent morpheme.

See also: -sion suffix, -tion, English morphology, Etymology of English noun-forming suffixes.