Origin: Germanic Old English suffix
Unthought has 4 different meanings across 1 category:
That which has not been (yet) thought; that which has yet to enter into the mind; a non-existent thought.
simple past tense and past participle of unthink
so unexpected as to have not been imagined
"an unhoped-for piece of luck"
"an unthought advantage"
"an unthought-of place to find the key"
Not having been thought.