observant
1. [ adjective ] paying close attention especially to details
Related terms: attentive
2. [ adjective ] quick to notice; showing quick and keen perception
Synonyms: observing
Related terms: perceptive
3. [ adjective ] (of individuals) adhering strictly to laws and rules and customs
Synonyms: law-abiding
Examples:

"law-abiding citizens" "observant of the speed limit"

Related terms: lawful
Similar spelling:   observantly
  observance
  observatory
  observation
  observably
  observable
  observe
  observer
  observed
  observing
  observingly