Invisible light includes ultraviolet and infrared rays.
This substance exists in an invisible state.
見えない is the everyday word for 'cannot be seen', while 不可視 is a formal, technical term.
可視 means 'visible, able to be seen' while 不可視 means 'invisible, not able to be seen', the direct technical opposite.
Compound of 不 (not) + 可 (possible) + 視 (see), literally 'not possible to see'. A Sino-Japanese term used in technical and formal contexts.