a letter written in 'invisible ink' [=ink that can only be seen when it is specially treated in some way]
It felt like I was 'invisible' at the party. [=no one was paying any attention to me at the party]
With the telescope we can see details of the planet's surface that are ordinarily 'invisible'.
(..) Listen to me. We only have a couple hours of light left. We gotta stash these pelts ... ...and get rid of the boat, let's go. Yes, captain. I told you to be invisible, son. - At least ... - If you want to survive keep your... ...mouth shut. - At least he heard me ... - They don't hear your voice! (..)2015 The Revenant