Synonyms of the word

observant

• adj. Alert and paying close attention; watchful.
• adj. Diligently attentive in observing a law, custom, duty or principle; regardful; mindful.

attentive

• adj. Paying attention; noticing, watching, listening, or attending closely.

law-abiding

• adj. Obeying the laws of society; not a lawbreaker; without a criminal record.

lawful

• adj. Conforming to, or recognised by law or rules.

observing

• v. present participle of observe.
• n. observation.

perceptive

• adj. having or showing keenness of perception, insight, understanding, or intuition.