absent-minded
Forgetful or inattentive of everyday details or duties, possibly due to a preoccupation with other thoughts. My absent-minded housemate is always lost in composing new poems and never remembers to clean the house or take out the trash!
AWOL
acronym Absent without leave. Having gone missing suddenly and without warning. It is originally a military phrase for one who leaves his or her post or duties without permission but without intention to desert. In colloquial usage, it can be used as an adverb or an adjective. The printer from the third floor is AWOL, does anyone know where it went? Jerry went AWOL after a few drinks. None of us even knew he had left until half an hour later.
long absent, soon forgotten
The longer a person is not present, the easier he or she is to forget about. A: "Is Carrie really dating someone else now?" B: "You've been gone for months! Long absent, soon forgotten."
absent (oneself) from
To leave a place, often to avoid something. If my ex-boyfriend does come, I'm going to absent myself from the party.
absent without leave
Not present for a duty or situation without permission. The phrase is usually used in reference to military service, and is often abbreviated with the acronym "AWOL." The young soldier was arrested for being absent without leave.
absent-minded professor
An otherwise intelligent person who often lacks common sense or forgets or overlooks important details. Louis is brilliant, but he's such an absent-minded professor when it comes to remembering to attend important meetings.
absent oneself from someone or something
to remain away from or avoid someone or some place. Fred absented himself from the meeting, which he was certain would be boring.
*absent without leave
absent from a military unit without permission; absent from anything without permission. (AWOL is an abbreviation. This is a serious offense in the military. *Typically: be ~; go ~.) The soldier was taken away by the military police because he was absent without leave.
absent-minded professor
a bumbling professor who overlooks everyday things. Fred is such an absent-minded professor. He'd forget his head if it wasn't screwed on.