These words refer to a mind that is lost in thought, lacks alertness or awareness or is given over to some matter other than the one at hand. Oblivious stresses lack of awareness, either because of deep thought or poor concentration: so fascinated with solving the problem that he was oblivious of the odd looks his fellow passengers were giving him; wandering thoughts that made him oblivious of the question the teacher had just asked him. Inattentive stresses exclusively this last possibility of oblivious, indicating an inability to keep the mind focused on the subject before it: inattentive to the demonstration the diving instructor was making of each position. This inability can be the result of restlessness, distraction, weak intellectual powers or even a wilful indifference to detail: children who grow inattentive during long class periods; a bored secretary, inattentive while taking dictation.

Abstracted stresses a mind that is far removed from mundane considerations before it, especially because of obsessive or intrusive thoughts and feelings: so abstracted by the beauty of the sunset that he quite forgot about the presence of his companions; the abstracted smile the widow gave to other mourners at the funeral. Absent-minded may function exactly like abstracted at a more informal level. More importantly, it is unique among these words in pointing to a fixed or ingrained tendency to lose one’s bearing because of intrusive concerns: the typical absent-minded professor, rapt in solving an equation while crossing against a red light; An absent-minded movement of his hand caused the cup to fall.