The quality of being intent and concentrated:
— The intentness of his gaze.

synonym: engrossment.

Roget 457: attention; mindfulness, presence of mind etc. adj.; intentness, intentiveness^†; alertness; thought etc. 451; advertence, advertency^†; observance, observation; consideration, reflection, perpension^†; heed; heedfulness; particularity; notice, regard etc. v.; circumspection, diligence etc. (care) 459; study, scrutiny inspection, introspection; revision, revisal.    active application, diligent application, exclusive application, minute application, close application, intense application, deep application, profound application, abstract application, labored application, deliberate application, active attention, diligent attention, exclusive attention, minute attention, close attention, intense attention, deep attention, profound attention, abstract attention, labored attention, deliberate attention, active thought, diligent thought, exclusive thought, minute thought, close thought, intense thought, deep thought, profound thought, abstract thought, labored thought, deliberate thought, active study, diligent study, exclusive study, minute study, close study, intense study, deep study, profound study, abstract study, labored study, deliberate study.    minuteness, attention to detail.    absorption of mind etc. (abstraction) 458.    indication, calling attention to etc. v.. ... show more

Roget 682: activity; briskness, liveliness etc. adj.; animation, life, vivacity, spirit, dash, energy; snap, vim.    nimbleness, agility; smartness, quickness etc. adj.; velocity, etc. 274; alacrity, promptitude; despatch, dispatch; expedition; haste etc. 684; punctuality etc. (early) 132.    eagerness, zeal, ardor, perfervidum aingenium [Lat.], empressement [Fr.], earnestness, intentness; abandon; vigor etc. (physical energy) 171; devotion etc. (resolution) 604; exertion etc. 686.    industry, assiduity; assiduousness etc. adj.; sedulity; laboriousness; drudgery etc. (labor) 686; painstaking, diligence; perseverance etc. 604.1; indefatigation^†; habits of business.    vigilance etc. 459; wakefulness; sleeplessness, restlessness; insomnia; pervigilium^†, insomnium^†; racketing.    movement, bustle, stir, fuss, ado, bother, pottering, fidget, fidgetiness; flurry etc. (haste) 684.    officiousness; dabbling, meddling; interference, interposition, intermeddling; tampering with, intrigue.    press of business, no sinecure, plenty to do, many irons in the fire, great doings, busy hum of men, battle of life, thick of the action.    housewife, busy bee; new brooms; sharp fellow, sharp blade; devotee, enthusiast, zealot, meddler, intermeddler, intriguer, busybody, pickthank^†; hummer, hustler, live man [U.S.], rustler [U.S.].    ... show more