1. Exceedingly harmful
   - deadly, pernicious, pestilent 
2. Deadly or sinister
   - baleful

See also: maleficent, noxious

• basidiosporous
• basidium
• basifixed
• basify
• basil
• basil balm
• basil mint
• Basil of Caesarea
• Basil the Great
• basil thyme
• basilar
• basilar artery
• basilar membrane
• basilary
• basileus
• basilic vein
• basilica
• basilican
• Basilicata
• Basiliscus
• basilisk
• basin
• basinal
• basined
• basinet