a.

1. 嚴格遵守……的[（+of）]
   A careful driver is observant of the traffic rules.

   謹慎小心的駕駛者嚴格遵守交通規則。

2. 觀察力敏銳的
   An observant journalist notices things that other people may not be aware of.

   觀察敏銳的記者會注意到其他人也許沒察覺的事物。

3. （觀察）仔細的；細心的；注意的
   The nurse is very observant to her patient's needs.

   那位護士非常注意她的病患的需求。

adj.

1. quick to notice things.
2. observing the rules of a religion.

n.