1. Causing fear or dread or terror
   "horrendous explosions shook the city"
   - awful, dire, direful, dread, dreaded, dreadful, fearful, fearsome, frightening, horrific, terrible

See also: alarming

• Helena
• Helene
• Helenium
• Helenium autumnale
• Helenium hoopesii
• Helenium puberulum
• Heleodytes
• heli-
• heliac
• heliacal
• Heliamphora
• helianthemum
• Helianthemum canadense
• Helianthemum scoparium
• helianthus
• Helianthus angustifolius
• Helianthus annuus
• Helianthus giganteus
• Helianthus laetiflorus
• Helianthus maximilianii
• Helianthus petiolaris
• Helianthus tuberosus
• helical
• Helichrysum
• Helichrysum bracteatum