Where does “tos” come from?

tos (Old French) comes from Latin tussem, from Latin tussis, from Proto-Italic tussis, from Proto-Indo-European tud-ti-s, from Proto-Indo-European (s)tewd-, from Proto-Indo-European stew- — to praise, laud.

Ancestry of “tos”, step by step

tos traces back through two separate lines of ancestry.

via Latin tussem

StepLanguageWordMeaning
1Latintussemaccusative singular of tussis
2Latintussiscough
3Proto-Italictussis—
4Proto-Indo-Europeantud-ti-scough
5Proto-Indo-European(s)tewd-to push, to hit
6Proto-Indo-Europeanstew-to praise, laud

via Latin tuus

StepLanguageWordMeaning
1Latintuusyour
2Proto-Italictowosyour
3Proto-Indo-Europeantúh₂you, thou
Every word from Proto-Indo-European stew- →Every word from Proto-Indo-European (s)tewd- →Every word from Proto-Indo-European tud-ti-s →