As an abstraction on the size of a CPU register, it really turned out to be more confusing than useful.
On RISC machines, it can be very useful to have the concept of "words," because that indicates things about how the computer loads and stores data, as well as the native instruction size. In DSPs and custom hardware, it can indicate the only available datatype.
The land of x86 goes to great pains to eliminate the concept of a word at a silicon cost.
Fortunately we have `register_t` these days.