ETYM Latin observatio: cf.French observation.
1. A patient visual study or examination; SYN. observance, watching.
2. A remark expressing careful consideration; SYN. reflection, reflexion.
3. Explicit notice; SYN. remark.
4. Facts learned by observing.
5. The act of making and recording a measurement.
In science, the perception of a phenomenon—for example, examining the Moon through a telescope, watching mice to discover their mating habits, or seeing how a plant grows.
Traditionally, observation was seen as entirely separate from theory, free from preconceptions and therefore lending support to the idea of scientific objectivity. However, as the preceding examples show, observations are ordered according to a pre-existing theory; for instance, one cannot observe mating behavior without having decided what mating behavior might look like. In addition, many observations actually affect the behavior of the observed (for instance, of mating mice).