1. Causing fear or anxiety by threatening great harm
   "a life-threatening disease"
   - dangerous, grave, grievous, serious, severe

See also: critical

• actinometer
• actinometric
• actinometrical
• actinometry
• actinomorphic
• actinomorphous
• actinomyces
• Actinomycetaceae
• actinomycetal
• Actinomycetales
• actinomycete
• actinomycetous
• actinomycin
• actinomycosis
• actinomycotic
• Actinomyxidia
• actinomyxidian
• actinon
• actinopod
• Actinopoda
• actinotherapy
• Actinozoa
• actinozoan
• action
• action at law