The Collaborative International Dictionary of English v.0.48:

Direful \Dire"ful\, a. [Dire + -ful.]
   Dire; dreadful; terrible; calamitous; woeful; as, a direful
   fiend; a direful day. -- Dire"ful*ly, adv. --
   Dire"ful*ness, n.
   [1913 Webster]