1. Lacking sense or discretion
   - rattlebrained, rattlepated, scatty [Brit] 
2. Guided by whim and fancy
   - flighty, flyaway, head-in-the-clouds

See also: foolish, frivolous

• scarab
• scarabaean
• scarabaeid
• scarabaeid beetle
• Scarabaeidae
• scarabaeus
• Scarabaeus sacer
• Scaramouch
• Scaramouche
• scarce
• scarcely
• scarceness
• just about
• just as
• just deserts
• just desserts
• just in case
• just in time
• just now
• just right
• just so
• just the ticket
• just then
• just-noticeable difference
• justice