Where does “sinisterity” come from?

sinisterity (English) comes from English sinister, from Middle English sinistre, from Old French sinistra, from Latin sinestra — left hand.

Ancestry of “sinisterity”, step by step

sinisterity traces back through two separate lines of ancestry.

via English sinister

StepLanguageWordMeaning
1EnglishsinisterInauspicious, ominous, unlucky, illegitimate;...
2Middle Englishsinistreunlucky
3Old Frenchsinistraleft
4Latinsinestraleft hand

via English ity

StepLanguageWordMeaning
1Englishity
2Ingrian-uUsed to form nouns from verbs
Every word from Latin sinestraEvery word from Old French sinistraEvery word from Middle English sinistre