The only free and comprehensive online etymological dictionary of the Spanish language
cacho (1) m. (Noun) "piece," "slice," "chunk"
Very late 15th cent. Originally meaning a pottery sherd. From Vulgar Latin *cacculus "pot," from Late Latin caccubus 'id.' Borrowed from Ancient Greek κάκκαβος 'id.' Of unknown origin, however compare Akkadian kukkubbu, kukkupu "rhyton," "pig's stomach" - if such a similarity is due to anything more than coincidence, we may posit an origin in a Semitic source.
Asturian cachu, Portuguese caco, Galician cacho