chiplet
Beginner
A small chip made to be joined with others in one package, so together they act like one big chip.
Novice
A die (one piece of silicon cut from the wafer) designed to be assembled with other dies in a single package and connected to them by short, dense links, so together they behave like one larger chip.
Expert
A die whose interfaces, test and power delivery assume multi-die integration. Splitting a design into chiplets lets each piece use the process that suits it and improves yield, at the cost of die-to-die power, latency and package cost.
Explained in AI accelerators and datacenter (Industries).
See also: silicon interposer, UCIe.