Wafer
Beginner
A thin, mirror-polished disc of very pure silicon. Hundreds of chips are built side by side on one wafer and cut apart at the end.
Novice
A slice of single-crystal silicon, today usually 300 mm across and under a millimeter thick, cut from a large crystal ingot and polished. Each copy of a chip on it is a die.
Expert
Czochralski-grown, (100)-oriented for CMOS, lightly doped, often with an epitaxial top layer. Film thickness and flatness are worst near the edge, so an edge exclusion ring is written off and edge dies yield worse.