Definitions:
imitative of the work of another artist, writer, etc., and usually disapproved of for that reason

(of a product) having a value deriving from an underlying variable asset

something which is based on another source

an arrangement or product (such as a future, option, or warrant) whose value derives from and is dependent on the value of an underlying asset, such as a commodity, currency, or security

an expression representing the rate of change of a function with respect to an independent variable.