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'.
(..) - Are you coming back to bed? - Yeah, yeah. I'll be right there, babe. Hi, Elaine. What did you think of the coffee table? It's invisible. So is everything cool or what? Yeah, you seem a little bit dysfunctional. - Well... - Come on, Elaine... (..)1991 TvShow: Seinfeld Title: The Truth Season: 3 Episode 2
(..) - No. Come on up. Can you believe somebody threw this out? I'm gonna make a coffee table out of this and surprise Tina. Well, wouldn't it be invisible? I mean, what, are you gonna just sense it's in front of the couch? Well... Hello. Hello. (..)1991 TvShow: Seinfeld Title: The Truth Season: 3 Episode 2