Definition
To be 'invisible' means something is impossible to see. It cannot be perceived by the eyes, either literally or figuratively. Unlike something that's simply hidden, 'invisible' things are undetectable by sight alone. Think of the classic invisibility cloak from Harry Potter; the wearer becomes unseen. Something can also be 'invisible' in the sense of being ignored or overlooked. Feeling invisible at a party is like being a ghost. The value of hard work can sometimes be invisible to those who only see the results.