n.1 the act or an instance of noticing; the condition of being noticed.
2 perception; the faculty of taking notice.
3 a remark or statement, esp. one that is of the nature of a comment.
4 a the accurate watching and noting of phenomena as they occur in nature with regard to cause and effect or mutual relations. b the noting of the symptoms of a patient, the behaviour of a suspect, etc.
5 the taking of the sun's or another heavenly body's altitude to find a latitude or longitude.
6 Mil. the watching of a fortress or hostile position or movements.
Phrases and idioms:
observation car esp. US a carriage in a train built so as to afford good views. observation post Mil. a post for watching the effect of artillery fire etc. under observation being watched.
observational adj. observationally adv.
Etymology: ME f. L observatio (as OBSERVE)