Is Optical Visible?

[hazelm]

The answer to this question seems so obvious that it is almost embarrassing to post it.  But, given that the world of science seems to change definitions in myriads of ways - heavens!  even proteins are another whole category - I ask anyway.

 

I was reading a very good article called "What is Light?".  Along the way, the author says most of us tend to think of light as  the part that is "visible" to us.  He then goes on to list the entire electromagnetic spectrum.  In that list, he does not list "visible" but does list "optical".  Please tell me these two words are synonymous in this situation.  Or maybe - it just occurs to me - the optical part includes the visible plus other elements?