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

See also: maleficent, noxious

• spur gear
• spur track
• spur wheel
• spur-of-the-moment
• spurge
• spurge family
• spurge laurel
• spurge nettle
• spurion
• spurious
• spurious correlation
• spurious wing
• spuriously
• spuriousness
• spurn
• spurned
• spurner
• spurred gentian
• spurrey
• spurring
• spurry
• spurt
• spurting
• spurtle
• sputnik