Where does “cái tôi” come from?

cái tôi (Vietnamese) comes from Vietnamese tối, from Vietnamese tí, from Middle Chinese 子, from Proto-Sino-Tibetan *tsəʔ — child, son, offspring; grandson; relatives; nephew/niece.

cái tôi (Vietnamese): an ego

Definitions

an ego

Ancestry of “cái tôi”, step by step

cái tôi traces back through 3 separate lines of ancestry.

via Vietnamese tối

Step	Language	Word	Meaning
1	Vietnamese	tối	dark; the duration from the late evening to the...
2	Vietnamese	tí	breast; a little bit; tiny; small
3	Middle Chinese	子	—
4	Proto-Sino-Tibetan	*tsəʔ	child, son, offspring; grandson; relatives; nephew/niece

via Latin egō

Step	Language	Word	Meaning
1	Latin	egō	I; first person singular personal pronoun, nominative case
2	Proto-Italic	egō	I
3	Proto-Indo-European	éǵh₂	I

via Vietnamese cái

Step	Language	Word	Meaning
1	Vietnamese	cái	a thing; a whatsit; the solid bits of a broth;...
2	Proto-Vietic	-keːʔ	woman, female

Every word from Proto-Sino-Tibetan *tsəʔ →Every word from Middle Chinese 子 →Every word from Vietnamese tí →