scatterbrained
1. [ adjective ] lacking sense or discretion
Synonyms: rattlepated scatty rattlebrained
Examples:

"his rattlebrained crackpot ideas" "how rattlepated I am! I've forgotten what I came for"- Glenway Westcott

Related terms: foolish
2. [ adjective ] absent-mindedly irresponsible
Synonyms: head-in-the-clouds flighty
Examples:

"he said I was too flighty to be a good supervisor"

Related terms: irresponsible
Similar spelling:   scatterbrain
  scatter_pin
  scattergood