Aren't all words "made up"? They all came into existence somehow. 
And pinch to zoom (as someone already pointed out) is still correct. The word zoom doesn't specifically mean "make it bigger", it simply means you are changing how large/small the subject appears. Zooming out is still zoom.
Trying to apply conventional linguistics to terms used in modern technology is senseless. The industry/field/culture that spawns the term is the ultimate deciding faction on proper use and pronunciation, even if the word already exists with another meaning and/or pronunciation.

And pinch to zoom (as someone already pointed out) is still correct. The word zoom doesn't specifically mean "make it bigger", it simply means you are changing how large/small the subject appears. Zooming out is still zoom.
Trying to apply conventional linguistics to terms used in modern technology is senseless. The industry/field/culture that spawns the term is the ultimate deciding faction on proper use and pronunciation, even if the word already exists with another meaning and/or pronunciation.