Where does “(ec)cu + illu” come from?

(ec)cu + illu (Vulgar Latin) comes from Latin illum, from Latin ille, from Latin olle, from Proto-Italic *olnos — that.

Ancestry of “(ec)cu + illu”, step by step

(ec)cu + illu traces back through two separate lines of ancestry.

via Latin illum

StepLanguageWordMeaning
1Latinillumaccusative masculine singular of ille
2Latinillethat; those; "; demonstrative pronoun "; that...
3LatinolleArchaic form of ille
4Proto-Italic*olnosthat

via Latin ecce

StepLanguageWordMeaning
1Latineccesee!, look!, behold!, points out something with...
2Latin-ceaffixed, usually to demonstratives, forming...
3Proto-Italickehere
4Indo-European*ḱe
Every word from Proto-Italic *olnosEvery word from Latin olleEvery word from Latin ille