The only free and comprehensive online etymological dictionary of the Spanish language
de (Preposition) "of," "from"
10th cent. Vulgar Latin de (Peregrinatio, 4th cent.) (Already assuming the roles of ab "by" and ex "out of" in Classical Latin). From Latin de "of." From Proto-Italic * 'id.' From Proto-Indo-European *deh1- "by means of (this) here," instrumental of *de "here."
Indo-European
Romance
Asturian de, Portuguese de, Galician de, Catalan de, French de, Italian di, Eastern Vuglar Latin Aromanian di, Romanian de
Italic
Oscan dat, Umbrian da-, Faliscian de (borrowed from Latin?)
Celtic
Old Irish de, Old Welsh di
Germanic
Old High German zuo "to," Old Saxon 'id.,' English to
Hellenic
Ancient Greek δή (dé) "even"