A cascading cipher (cascade) consists of several building blocks which are more primitive ciphers. A cascade is a combination of different ciphers, performed sequentially.
The easiest ones are only a repetition of the same concept (e.g. mono-alphabetic substitution). To make ciphers more secure combinations of substitution followed by transposition have been built (see ADFGVX encryption).
All modern ciphers consist of more primitive building blocks.