a. 1. Full of dread or terror; fearful. [ Obs. ] “With dreadful heart.” Chaucer. [ 1913 Webster ]
2. Inspiring dread; impressing great fear; fearful; terrible; as, a dreadful storm. “ Dreadful gloom.” Milton. [ 1913 Webster ]
For all things are less dreadful than they seem. Wordsworth. [ 1913 Webster ]
3. Inspiring awe or reverence; awful. [ Obs. ] “God's dreadful law.” Shak.
Syn. -- Fearful; frightful; terrific; terrible; horrible; horrid; formidable; tremendous; awful; venerable. See Frightful. [ 1913 Webster ]
adv. In a dreadful manner; terribly. Dryden. [ 1913 Webster ]
n. The quality of being dreadful. [ 1913 Webster ]