1. Causing fear or dread or terror
   - awful, dire, direful, dread, dreaded, dreadful, fearful, frightening, horrendous, horrific, terrible

See also: alarming, fearsomely

• brain death
• brain disease
• brain disorder
• brain doctor
• brain drain
• brain edema
• brain fever
• brain fingerprinting
• brain mushroom
• brain science
• brain sugar
• brain surgeon
• brain surgery
• brain trust
• brain truster
• brain tumor
• brain tumour
• brain-fag
• brain-teaser
• brainbox
• braincase
• class Asteroidea
• class Aves
• class Bacillariophyceae
• class Basidiomycetes