Sanskrit एकाग्र, "unperplexed, undisturbed, intent, closely attentive, fixing one's attention upon one point or object, having one point, one-pointed, concentrated." Also as ekagrata एकाग्रता (close and undisturbed attention), ekagram एकाग्रम् (close and undisturbed attention).
In Patanjali's Yoga Sutras, the fourth bhumika (stage of concentration). Vikshipta refers to the stage of concentration where attention is concentrated.
"Kshipta, Mudha, Vikshipta, Ekagra and Niruddha are the five Yogic Bhumikas. The Chitta or mind manifests itself in five different forms. In the Kshipta state, the rays of the mind are scattered on various objects. It is restless and jumps from one object to another. In the Mudha state, the mind is dull and forgetful. Vikshipta is the gathering mind. It is occasionally steady and, at other times, distracted. By practice of concentration, the mind struggles to gather itself. In the Ekagra state, it is one-pointed. There is only one idea present in the mind. The mind is under perfect control in the Niruddha state. Dharana is practised for stopping the modifications of the mind." - Swami Sivananda