Lisp: cons, car and cdr

There is a footnote in chapter 2 of SICP that explains what the names of these popular Lisp primitives stand for -

The name cons stands for “construct.” The names car and cdr derive from the original implementation of Lisp on the IBM 704. That machine had an addressing scheme that allowed one to reference the “address” and “decrement” parts of a memory location. car stands for “Contents of Address part of Register” and cdr (pronounced “could-er”) stands for “Contents of Decrement part of Register.”