What Does Word Size Mean?
In computing, word size refers to the maximum number of bits that a CPU can process at a time. A word is a fixed-sized piece of data which is dictated by the processor hardware architecture; fixed in a sense that it is the maximum size that the processor is always using, yet variable in the sense that word sizes vary amongst processor architectures, most notably because of generation and the state of technology.
Techopedia Explains Word Size
Word size has varied in size and even in meaning throughout the history of the computer. Originally, “word” meant 16 bits, as that was the maximum possible value at the time. But as processor hardware technology progressed and computers were able to handle larger and larger amounts of data, word simply became the maximum possible number of bits that the processor in question can process. So word size could be as low as 4 bits or as high as 64 bits, depending on what a particular processor can handle.