Nouns

(n)observationthe act of making and recording a measurement
(n)observation, observance, watchingthe act of observing; taking a patient look
(n)observation, reflection, reflexiona remark expressing careful consideration
(n)observationfacts learned by observing“he reported his observations to the mayor”
(n)notice, observation, observancethe act of noticing or paying attention“he escaped the notice of the police”