They had seldom seen him eat so heartily at any table but his own, and never before known him so little disconcerted by the melted butter’s being oiled.
The Tilneys called for her at the appointed time; and no new difficulty arising, no sudden recollection, no unexpected summons, no impertinent intrusion to disconcert their measures, my heroine was most unnaturally able to fulfil her engagement, though it was made with the hero himself.
There are no more uses of "disconcerting" in the book.
Show samples from other sources
It was disconcerting to realize the experts don’t really understand what is going on either.
Changing teachers in the middle of the semester was disconcerting.