What does it mean by word size in computer?

Question

I have tried to get a grasp of what \"word\" means and I have looked in the wiki and the definition is vague. So my question is what is \"word size\

Answer 1

One answer is -- not as much as it used to. Way back when, computers could only load/store full "words" of memory, which would be 16/24/32/36/48 bits each (depending on the particular machine). One would have to carefully structure their program design around the word size of the target machine.

But any more computers can access individual bytes or can access strings of data dozens of bytes long, with one relatively seamless operation. Much more significant than the technical word size is the memory buss width, which determines how many bytes can be transferred between CPU and memory in one memory "cycle".

So "word size" is somewhat meaningless, and (as another answer suggests) companies like Microsoft will often define it in an arbitrary manner, with no real relationship to anything.