Delete an app completely (special case) and question regarding empty trash I downloaded a game and deleted it by just Holding it for few second and click x on the launchpad, because I can still see it occupies 20 GB in my hard disk which is truly annoying. Does it mean it wasn't removed completely?

It seems the Mac can empty the trash securely or not securely? 
Does it mean whatever deleted in the trash (even you empty the trash) is possible to recover? Unless you press the Empty trash securely?
Thanks 
I feel like I'm so stupid, because I lost 40 GB by just doing deleting and downloading .... BUT I wouldn't lose any disk space if it 's microsoft window... this makes me feel really uncomfortable.. SSD is already very limited disk...

HOW can I get it back and delete it completely ? Is there any apps allow me to do so?  THANKS
N.B.I'm currently using the newest model of Mac book pro.

Situation: I deleted the file (by just holding it for few second and press the cross) but it still occupied 20 GB... Is there any way to get the space back?
All the apps installed from the App Store are stored in the /Applications folder.
Go to the Applications folder (Finder menu -&gt; Go -&gt; Applications or check the Finder window sidebar for this folder), check if the app you want to delete is present there. If it isn't, then it's gone. Else, move it to Trash and then empty it.

If it doesn't help, please clarify how are you determining that 20GB is still occupied by the app.