Where does “unfastenable” come from?

unfastenable (English) comes from English unfasten, from English fasten, from Middle English fastenen, from Old English fæstnian, from Proto-West Germanic fastinōn, from Proto-West Germanic fast, from Proto-Germanic fastuz — fixed, firm, secure.

unfastenable (English): Not fastenable; Able to be unfastened

Definitions

  1. Not fastenable; Able to be unfastened

Ancestry of “unfastenable”, step by step

unfastenable traces back through two separate lines of ancestry.

via English unfasten

StepLanguageWordMeaning
1EnglishunfastenTo detach from any connecting agency or link; to...
2EnglishfastenTo attach or connect in a secure manner; To cause...
3Middle Englishfastenen
4Old Englishfæstnianto fasten or fix; to establish
5Proto-West Germanicfastinōnto fasten, to make fast
6Proto-West Germanicfastfixed, fast
7Proto-Germanicfastuzfixed, firm, secure

via English fastenable

StepLanguageWordMeaning
1EnglishfastenableCapable of being fastened
2English-ableAn adjectival suffix; forms adjectives meaning
3Middle English-ableable
4Old French-ableworthy of, deserving of; -ing, creating an...
5Latin-ābilissuffixed to noun to form adjectives meaning "able to have or bring, prone to have or bring, having the power to have or bring": -able
Every word from Proto-Germanic fastuz