Observant (adjective)

1. Paying close attention to something, noticing details.
2. Careful to obey rules and customs.

Origin:

The word "observant" comes from the latin word "observantem" which means "to watch, pay attention to".

Examples:

1. She was very observant and noticed the small details of the scene.
2. An observant driver is always aware of their surroundings.
3. He was observant of the customs and traditions of the country he was visiting.
4. An observant person would have noticed the mistake.
5. The observant teacher noticed the student was having trouble.