Where does “cê-cedilha” come from?

cê-cedilha (Portuguese) comes from Portuguese cê, from Portuguese você, from Portuguese vosmecê, from Portuguese vossemecê, from Old Portuguese vossa mercee, from Latin vostra, from Latin voster, from Latin vester — Contrastive or oppositional adjectival suffix.

Ancestry of “cê-cedilha”, step by step

cê-cedilha traces back through two separate lines of ancestry.

via Portuguese

StepLanguageWordMeaning
1Portuguesecee; you
2Portuguesevocêyou; you; one
3PortuguesevosmecêArchaic form of você
4PortuguesevossemecêArchaic form of você
5Old Portuguesevossa mercee
6LatinvostraAlternative form of vestra
7LatinvosterAlternative form of vester; your, plural...
8Latinvesteryour, yours, of you
9Proto-Italicwesterosyour
10Proto-Indo-European-terosContrastive or oppositional adjectival suffix

via Portuguese cedilha

StepLanguageWordMeaning
1Portuguesecedilhacedilla
2SpanishcedillaName of the letter ç; cedilla
3Old SpanishcedaThe name of the Latin-script letter Z
4Latinzēta
5Ancient Greekζῆταzeta, the name for the sixth letter Ζ, ζ of the...
6Phoenician𐤆this
7Egyptian?
Every word from Proto-Indo-European -terosEvery word from Proto-Italic westerosEvery word from Latin vester