aghast

 
Pronunciation: /əˈgɑːst/

adjective

[predic.]
  • filled with horror or shock: she winced, aghast at his cruelty

Origin:

late Middle English: past participle of the obsolete verb agast, gast 'frighten', from Old English gǣsten. The spelling with gh (originally Scots) became general by about 1700, probably influenced by ghost; compare with ghastly