Self-referential data structure
Programming[1]
A self-referential structure is one of the data structures which refer to the pointer to (points) to another structure of the same type. For example, a linked list is supposed to be a self-referential data structure. The next node of a node is being pointed, which is of the same struct type. [2]
It is a special type of structure which contains a member of its own type. The member of its own type is actually a pointer variable of same structure in which it is declared.[3]
Within the context of blockchain, each block is linked to a previous or next node, much like a linked list.