Caddr

Following the SEL in the control list are two elements (the cadr and caddr of the C list), both of which are themselves lists of instructions.

Source: wiktionary

For example, in a procedure that manipulates a list data stream, we might know that the mode of the car of the list (that is the current message) is the same mode as the cadr (second message), caddr (third message), etc.

Source: wiktionary

If we let x denote the tree (1 2 3), then the car of x is 1, the cdr of x is (2 3), the cadr of x is 2, the caddr of x is 3, and the cdddr of x is nil.

Source: wiktionary

In effect, lazy evaluation would force things to happen in the proper order: The car of output is the first prompt. The cadr of output is the first square, a value that requires evaluation of the car of input. The caddr of output is the second prompt.

Source: wiktionary