A chip package in which the total package size is no more than 20% greater than the size of the die within.
Chip scale package not much greater than the chip itself (typically not greater than 20% larger).
An integrated circuit package which is no more than 20% larger than the die.
A type of ball grid array in which the package is roughly the size of the die.
A popular description is that a CSP must be no more than 120% the X and Y dimensions of the silicon die within the package. So, the CSP is a die on a carrier substrate. In order to maintain the CSP die to package ratio the CPS is generally a ball grid array. So, this description becomes fuzzy because CSP fabricators routinely shrink the die to reduce cost, but generally do not change packaging.
A chip scale package (CSP) (sometimes, chip-scale package with a hyphen) is a type of integrated circuit chip carrier that has no pins or wires but uses contact pads instead. To be considered a CSP, a package must have an area no greater than 1.2 times that of the die packaged.