Definition of "awfulness"

Out came old Teenie, buzzing mad as a whole nest of wasps. Muttered awfulnesses came from her great padded bonnet.

1942, Emily Carr, “Characters”, in The Book of Small

"Why is the awfulness of families such a popular reason for starting another?"

1961, Peter De Vries, chapter 3, in The Blood of the Lamb, Penguin, published 1982, page 36

[…] the knocking at the gate, which succeeds to the murder of Duncan, produced to my feelings an effect for which I could never account: the effect was—that it reflected back upon the murder a peculiar awfulness and a depth of solemnity […]

1823, Thomas de Quincey, “On the Knocking at the Gate in Macbeth”, in Robert Morrison, editor, On Murder, Oxford World's Classics, published 2006, page 3