English▸ noun
1 [mass noun] the action or process of closely observing or monitoring something or someone:
she was brought into hospital for observation
units kept enemy forces under observation for days
[count noun] detailed observations were carried out on the students' behaviour.
▪ the ability to notice things, especially significant details:
his powers of observation.
▪ the act of taking the altitude of the sun or another celestial body to find a latitude or longitude.
– ORIGIN late Middle English (in the sense ‘respectful adherence to the requirements of rules or ritual’): from Latin observatio(n-), from the verb observare (see observe).