Synonyms of the word

ultraviolet

• adj. of electromagnetic radiation beyond (higher in frequency than) light visible to the human eye; radiation…
• n. Ultraviolet colour.

invisible

• adj. Unable to be seen; out of sight; not visible.
• adj. Not appearing on the surface.
• adj. (Internet) Apparently, but not actually, offline.
• adj. (psychology) That is ignored by a person.
• v. To invisiblize.
• n. (obsolete) An invisible person or thing; specifically, God, the Supreme Being.
• n. (obsolete) A Rosicrucian; so called because avoiding declaration of his craft.
• n. (obsolete) One of those (as in the 16th century) who denied the visibility of the church.

unseeable

• adj. invisible.
• adj. unimaginable.