Mindfulness

(skt.: smrti; tib.: dren pa) Sometimes also translated as recollection. It is mental factor which holds an object in mind and does not lose it. As Arya Asanga said in his Compendium of Knowledge: What is mindfulness? In regard to a familiar object, your mind is not forgetful and operates without distraction. 

Vasubandhus Commentary on the Ornament for the Mahayana Sutra also states: Mindfulness and introspection bring about close mental focus because the former prevents your attention from wandering from the object of meditation and the latter clearly recognizes that your attention is wandering.