The word "scatterbrain" refers to a person who often forgets things or has difficulty concentrating. It means their thoughts and ideas are scattered or all over the place, making it hard for them to stay focused. Full definition
I am leaving town for six months next year, so this was about to become a necessity soon anyway, but I immediately realized that for someone as scatterbrained as me their services are a godsend and I should have hired them long ago. (money.stackexchange.com)
I've been a little scatterbrained lately so please let me know if you come across any bugs while you're browsing the site. (ilovevegan.com)
We all have that one scatterbrained friend who loses her keys, her phone, and her wallet at least three times a week. (health.com)