2. <networking> IP address.
3. <networking> MAC address.
4. <storage, programming> An unsigned integer used to select one fundamental element of storage, usually known as a word from a computer's main memory or other storage device. The CPU outputs addresses on its address bus which may be connected to an address decoder, cache controller, memory management unit, and other devices.
While from a hardware point of view an address is indeed an integer most strongly typed programming languages disallow mixing integers and addresses, and indeed addresses of different data types. This is a fine example for syntactic salt: the compiler could work without it but makes writing bad programs more difficult.