Absent-minded a. : Absent in mind; abstracted; preoccupied.

Example:
Why am I being so absent minded when I try to think if I locked the car or doors of the house?

Taxonomy
Absent-mindedness, failures, memory failures, free encyclopedia, memory, Mental Lapses, Consciousness and Cognition, everyday life, everyday errors, Carriere, Cheyne, Consequences, cause accidents, search, different things, low level, intense attention, unwarranted.

Defination from the web:
Absent-minded memory failures occur when one is distracted with issues or concerns, and he/she is unable to focus on things needed to remember. ... Absent-minded? The Psychology of Mental Lapses and Everyday Errors. Englewood Cliffs: Prentice-Hall. Reason, J. T. (1984). Lapses of ...