superscribe vs superscription

superscribe is not a noun while superscription is a noun.

Word	Noun	Adjective	Verb	Adverb
superscribe	No	No	Yes	No
superscription	Yes	No	No	No

superscribe (noun)	superscription (noun)
	the activity of superscribing
	an inscription written above something else

superscribe (verb)	superscription (verb)
write on the outside or upper part of
write on the top or outside