The adj invisible has 2 senses (first 1 from tagged texts)
1. (8) invisible, unseeable -- (impossible or nearly impossible to see; imperceptible by the eye; "the invisible man"; "invisible rays"; "an invisible hinge"; "invisible mending")
2. inconspicuous, invisible -- (not prominent or readily noticeable; "he pushed the string through an inconspicuous hole"; "the invisible man")