scatterbrain
Someone who is very forgetful, unfocused, or disorganized. Sorry for forgetting about your recital. I've been such a scatterbrain, lately! We used to have a total scatterbrain managing our accounts, so things were all over the place for a while.
scatterbrain
n. a forgetful person; someone who is mentally disorganized. Aunt Martha is a real scatterbrain. She always forgets where her glasses are.