This word is very new to me, but it appears for the beginners. I didnt know its meaning, so I got it from freedictionary.com

‘any instruction that works first one way and then the other; it turns something on the first time it is used and then turns it off the next time’.

When we add one layer to the  all ready  existed map, itturns on itself on its own. We can make it appear or disappear.  Is it toggling?

Is toggling typical GiS word???

Try to toggle between data view and layout view!!