Synonyms and related words :
advertent, agile, agog, alert, alive, all ears, all eyes, assiduous, at it, at work, attentive, awake, aware, bright, busy, careful, concentrated, conscious, diligent, earnest, employed, engaged, finical, finicking, finicky, full of business, hard at it, hard at work, heedful, in harness, intense, intent, intentive, keen, meticulous, mindful, nice, niggling, nimble, observant, observing, occupied, on duty, on the, on the alert, on the ball, on the go, on the hop, on the jump, on the move, on the run, open-eared, open-eyed, openmouthed, prompt, qui vive, quick, ready, regardful, sharp, sleepless, smart, tied up, unblinking, unnodding, unsleeping, unwinking, wakeful, watchful, wide-awake, working