unstable / instability

elroy

Moderator: EHL, Arabic, Hebrew, German(-Spanish)
US English, Palestinian Arabic bilingual
Does anyone know why the adjective is “unstable” but the noun is “instability”?
 
  • Awwal12

    Senior Member
    Russian
    Well, they're basically formed independently in English (from "stable" and "stability" respectively), and the usage of the negative in- looks pretty chaotic in English, so I wouldn't be very surprised... Cf. also incivilization vs. uncivilized, etc.
     

    Frank78

    Senior Member
    German
    Does anyone know why the adjective is “unstable” but the noun is “instability”?

    They entered the English language at different times. The former is about 200-300 years older, it might have been loaned as "stable" and people just put their well-known Germanic negative prefix in front of it or the word "stable" underwent nativisation while "instability" could be directly loaned from Latin "instabilitas".
     
    Last edited:

    berndf

    Moderator
    German (Germany)
    They entered the English language at different times. The former is about 200-300 years older, it might have been loaned as "stable" and people just put their well-known Germanic negative prefix in front of it or they word "stable" underwent nativisation while "instability" could be directly loaned from Latin "instabilitas".
    :thumbsup:

    Both adjectives, unstable and instable are attested but the latter never seems to have caught on. If the number of quotations in the MED is any indication, the dominant noun was unstablenes(se) with unstabilite as a less frequent variant. With in- there are instable as an adjective and instabilite as a noun, but both have only few attestations.

    Early modern English (16th to 18th centuries) saw a wave of fresh Latin loans via educated registers. This seams to have raised the popularity of instability at the expense of unstableness and unstability. Why this didn't happen to the adjective, I can only speculate: The unstressed syllables in- and un- as they occur in the noun are phonetically much closer than the stressed ones as they occur in the adjectives and there might therefore have been more resistance to change with the adjectives than with the nouns.
     
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