1. Not allowing air or gas to pass in or out
   - airtight, air-tight

See also: tight

• unsectarian
• unsecure
• unsecured
• unsecured bond
• unseductive
• unseeable
• unseeded
• unseeing
• unseeingly
• unseemliness
• unseemly
• unseen
• unsegmented
• unsegregated
• unselected
• unselective
• unselfconscious
• unselfconsciously
• unselfconsciousness
• unselfish
• unselfishly
• unselfishness
• unsensational
• unsensible
• unsent