Invisible

4 clues
Unseen
Like a spy's ink?
Writer of unseen words?
Like Griffin in an H. G. Wells tale
Similar answers:
Accessible
Admissible
Admissionimpossible
Almostimpossible
Anythingpossible
Areweinvisible
Asfaraspossible
Bougainvillea
Captainvideo
Certainvictory
Collapsible
Declinedinvites
Defensible
Derisible
Diffusible
Divisible
Divisiblebyfour
Dontjustinviteanybody
Engravedinvitation
Enteruninvited