Where does “tu” come from?

tu (Galician) comes from Old Portuguese tu, from Latin tū, from Proto-Italic tū, from Proto-Indo-European túh₂ — you, thou.

tu (Galician): you

Definitions

Step	Language	Word	Meaning
1	Old Portuguese	tu	thou, you
2	Latin	tū	you (singular); thou
3	Proto-Italic	tū	you
4	Proto-Indo-European	túh₂	you, thou