Definition of "dreadfully"

At that moment a curious crack sounded inside the statue, as if something had broken. The fact is that the leaden heart had snapped right in two. It certainly was a dreadfully hard frost.

1888, Oscar Wilde, “The Happy Prince”, in The Happy Prince and Other Tales

“Here it is,” said Eddie. “‘Why Must it Always be Tomato Soup?’ It's so deeply true, don't you feel? Tomato soup is so dreadfully eternal.”

1918 August, Katherine Mansfield [pseudonym; Kathleen Mansfield Murry], “Bliss”, in Bliss and Other Stories, London: Constable & Company, published 1920, pages 135–136