ob·ser·va·tory [observatoryobservatories] BrE [əbˈzɜːvətri] NAmE [əbˈzɜːrvətɔːri] noun (pl. ob·ser·va·tories) a special building from which scientists watch the stars, the weather, etc.
Word Origin: late 17th cent.; from modern Latin observatorium, from Latin observat- ‘watched’, from the verb observare ‘to watch’, from ob- ‘towards’ servare ‘attend to, look at’.