1. In a harmfully insidious manner
   "these drugs act insidiously"
   - perniciously

See also: insidious

• sulphurette
• sulphuretted
• sulphuric
• sulphuric acid
• sulphurised
• sulphurous
• sulphury
• sultan
• Sultan of Swat
• sultana
• sultanate
• Sultanate of Oman
• sultrily
• sultriness
• sultry
• sum
• sum of money
• sum total
• sum-up
• sumac
• sumac family
• sumach
• Sumatra
• Sumatran
• Sumer