Where does “not’ve” come from?

not’ve (English) comes from English Not, from Middle English not, from Middle English nought, from Old English nōwiht, from Old English ne, from Old English ealles, from Old English -es, from Proto-Germanic -as — Creates action nouns or result nouns from verbs;...

Ancestry of “not’ve”, step by step

not’ve traces back through two separate lines of ancestry.

via English Not

StepLanguageWordMeaning
1EnglishNot
2Middle Englishnotnot; nothing, nought; nobody, no person
3Middle Englishnoughtnothing, none; not; iniquitous, wicked
4Old Englishnōwiht
5Old Englishnenot; or, and not; "ne... ne..." is used to mean "...
6Old Englisheallescompletely, wholly, entirely; totally,...
7Old English-espossessive marker, indicating that an object...
8Proto-Germanic-asused in formation of adverbs
9Proto-Indo-European-ēsPrimarily forms adjectival bahuvrīhi compounds
10Proto-Indo-European-ess
11Proto-Indo-European-osCreates action nouns or result nouns from verbs;...

via English ’ve

StepLanguageWordMeaning
1English’vein its sense marking the perfect or retrospective aspect
Every word from Proto-Indo-European -os