infrared vs unseeable

infrared is a noun but unseeable is not a noun.

Word	Noun	Adjective	Verb	Adverb
infrared	Yes	Yes	No	No
unseeable	No	Yes	No	No

infrared (noun)	unseeable (noun)
the infrared region of the electromagnetic spectrum; electromagnetic wave frequencies below the visible range
electromagnetic radiation with wavelengths longer than visible light but shorter than radio waves

infrared (adjective)	unseeable (adjective)
having or employing wavelengths longer than light but shorter than radio waves; lying outside the visible spectrum at its red end	impossible or nearly impossible to see; imperceptible by the eye