Alert

Alert:  fully aware, attentive, agile, wide-awake
Part of Speech: adjective
Origin: (according to dictionary.com)

c.1600, from Fr. alerte  "vigilant," from phrase à l'erte  "on the watch," from It. all'erta  "to the height," from erta  "lookout, high tower," orig. fem. of erto,  pp. of ergere  "raise up," from L. erigere  "raise." The adv. is the oldest form in Eng.; the adj. is from 1712, the noun from 1803, and the verb from 1868

Synonmys:

1. Active-adjective; engaged in action; characterized by energetic work, participation, etc.; busy: an active life. Origin: 1300–50; < L āctīvus
2. Attentive-adjective; characterized by or giving attention; observant: an attentive audience. Origin: 1375–1425; late ME (Scots
3. Enthralled-adjective; to be held spell-bound. Origin: 1570–80; en + thrall
4. Awake-adjective; waking; not sleeping, alert. Origin: bef. 1000; ME awaken,
5. Aware-adjective; having knowledge; conscious; cognizant: aware of danger. Origin: 1100; ME, var. of iwar,  OE gewær  watchful
6. Interested-adjective; having the attention or curiosity engaged. Origin: 1225–75; (n.) ME < ML, L: it concerns, lit., it is between; r. interesse
7. Heedful-adjective; taking heed; attentive; mindful; thoughtful; careful.Origin: 1540–50; heed + full
8. Vigilant-adjective; ever awake and alert; sleeplessly watchful. Origin: 1470–80; < L vigilant-  (s. of vigilāns ), prp. of vigilāre  to be watchful.
9. Observant-adjective; quick to notice or perceive; alert. Origin: 1425–75; late ME < F, prp. of observer.
10. Watchful-adjective; vigilant or alert; closely observant. Origin: 1540–50; watch + full.