Where does “sí” come from?

sí (Spanish) comes from Old Spanish sy, from Latin sīc, from Latin sice, from Latin sī, from Proto-Italic sei, from Proto-Indo-European só — this; that.

sí (Spanish): yes, affirmation. Commonly used to respond...

Definitions

yes, affirmation. Commonly used to respond...

Ancestry of “sí”, step by step

sí traces back through two separate lines of ancestry.

via Old Spanish sy

Step	Language	Word	Meaning
1	Old Spanish	sy	yes in response to a question
2	Latin	sīc	yes, indeed (If answering a question)
3	Latin	sice	—
4	Latin	sī	if, supposing that
5	Proto-Italic	sei	so, thus
6	Proto-Indo-European	só	this; that

via Latin sibi

Step	Language	Word	Meaning
1	Latin	sibi	the dative of the reflexive pronoun meaning to...
2	Proto-Indo-European	sébʰye	—
3	Proto-Indo-European	swé	self

Words derived from “sí”

si
si
si
siquiera
sino
simón
si si
sisi
simás
так єс сі
otrosí
Simon
simasito

Every word from Proto-Indo-European só →Every word from Proto-Italic sei →Every word from Latin sī →