"Invisible"

"Invisible" refers to something that cannot be seen with the naked eye, either because it is too small, transparent, or lacks physical presence detectable by sight. For example, gases like oxygen are invisible because they don’t reflect light, and some emotions or forces, such as gravity, are invisible but have measurable effects. The term highlights the limitations of human perception, while scientific or technological tools can often detect or measure what is invisible to the naked eye. It emphasizes that absence of sight does not equate to absence or nonexistence.