| scrupulous(adjective, thoughtful, sober, cautious, prudent) |
| sentient(adjective, understanding, keen, sensible, certain) |
| sharp(adjective, understanding, alert, familiar, intelligent) |
| wide awake(expression, adjective, correct, attentive, awake) |
| absorbed(adjective, attention, attentive) |
| alive to(verb, expression, adjective, phrasal verb, understanding) |
| appreciative(adjective, understanding, enthusiastic, alert, familiar) |
| apprised(adjective, understanding, keen, sensible, certain) |
| assiduous(adjective, thoughtful, sober, considerate, cautious) |
| conversant(adjective, understanding, keen, sensible, certain) |
| discreet(adjective, understanding, kind, friendly, deliberate) |
| in the know(expression, adjective, idiom, alert, familiar) |
| on the lookout(expression, adjective, idiom, adverb, alert) |
| on to(expression, adjective, understanding, keen, sensible) |
| active |
| astute(adjective, understanding, kind, friendly, polite) |
| chary(adjective, thoughtful, sober, aware, attentive) |
| cognisant |
| concentrating(adjective, considerate, responsive, aware, attentive) |
| concerned(adjective, understanding, kind, friendly, deliberate) |