1. In a meaningless and purposeless manner
   "these innocent bystanders were senselessly killed" 
2. In an unreasonably senseless manner
   - mindlessly

See also: senseless

• subarctic
• subartesian
• subatomic
• subatomic particle
• subaudition
• subbase
• subbing
• subclass
• subclass Acnidosporidia
• subclass Actinopoda
• subclass Alismatidae
• subclass Amphineura
• subclass Anapsida
• subclass Archaeornithes
• subclass Archosauria
• subclass Arecidae
• subclass Asteridae
• subclass Branchiopoda
• subclass Caryophyllidae
• subclass Cirripedia
• subclass Cnidosporidia
• subclass Commelinidae
• subclass Copepoda
• subclass Crossopterygii
• subclass Diapsida