Where does “nisi” come from?

nisi (Latin) comes from Latin sī, from Proto-Italic sei, from Proto-Indo-European só — this; that.

nisi (Latin): if not, unless, except; masculine genitive...

Definitions

  1. if not, unless, except; masculine genitive...

Ancestry of “nisi”, step by step

nisi traces back through two separate lines of ancestry.

via Latin sī

StepLanguageWordMeaning
1Latinsīif, supposing that
2Proto-Italicseiso, thus
3Proto-Indo-Europeansóthis; that

via Latin nī

StepLanguageWordMeaning
1Latinnīnot, if...not, unless- an absolutely negative particle like ne so only in combinations
Every word from Proto-Indo-European só →Every word from Proto-Italic sei →Every word from Latin sī →