Learner's definition of INVISIBLE
1 : impossible to see: not visible
Sound waves are invisible.
a thriller about an invisible man
With the telescope we can see details of the planet's surface that are ordinarily invisible.
It felt like I was invisible at the party. [=no one was paying any attention to me at the party]
She feels as if her success is being blocked by an invisible barrier.
Homelessness is no longer an invisible problem for this city.
a letter written in invisible ink [=ink that can only be seen when it is specially treated in some way]
2 chiefly British, finance — used to describe money from foreign countries that is received from providing services (such as banking and tourism) rather than from selling products