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

• Sparaxis tricolor
• spare
• spare part
• spare time
• spare tire
• spare tyre
• spare-time activity
• sparely
• spareness
• sparer
• sparerib
• spareribs
• Sparganiaceae
• Sparganium
• sparge
• sparge pipe
• sparger
• sparid
• sparid fish
• yclept
• yd
• yds
• ye
• yea
• yeah