Where does “SI” come from?

SI comes from French si, meaning "if," though its ultimate origin and semantic development remain uncertain.

SI (English): Initialism of signal integrity; Initialism of...

Definitions

  1. Initialism of signal integrity; Initialism of...

Ancestry of “SI”, step by step

SI traces back through two separate lines of ancestry.

via Middle English si

StepLanguageWordMeaning
1Middle Englishsi
2Italianyes; so
3Italianbeneupper-class, posh, high; well, nicely, OK, right;...
4Latinbenewell; properly, exactly; agreeably, favorably
5Latinbonusgood, honest, brave, noble, kind, pleasant;...
6Old LatinduenosAlternative form of duonus
7Proto-Italicdwenosgood
8Proto-Indo-Europeandew-to show favour, revere; to fail, to lag, to be...

via French SI

StepLanguageWordMeaning
1FrenchSISI
2Frenchtôtearly
3Old Frenchtostearly; soon; quickly; straight away
4Latintostumnominative neuter singular of tostus; accusative...
5Latintostusroasted, toasted, scorched, having been roasted;...
6Proto-Italic*torstos

Words derived from “SI

Every word from Proto-Indo-European dew-