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

• lady's tobacco
• lady's tresses
• lady's-eardrop
• lady's-eardrops
• lady's-finger
• lady-in-waiting
• lady-of-the-night
• lady-slipper
• ladybeetle
• ladybird
• ladybird beetle
• ladybug
• ladyfinger
• ladyfish
• ladylike
• ladylikeness
• ladylove
• Ladyship
• laelia
• Laertes
• laetrile
• laevo-
• laevorotatary
• laevorotatory
• laevulose