1 [count] : a statement about something you have noticed : a comment or remark
▪ I'm not criticizing that kind of clothing. I'm just making an observation about the style. ▪ Her constant observations about the weather bored me. synonyms ¹remark 2 a [noncount] : the act of careful watching and listening : the activity of paying close attention to someone or something in order to get information
▪ These facts are based on close observation of the birds in the wild. ▪ Children learn by observation. ▪ The author's excellent powers of observation [=ability to notice and pay close attention to things] are evident in the book's detailed descriptions. ▪ The plants seem to have recovered from the disease, but they are still under observation. [=someone is watching them carefully] ▪ He has been under government observation [=the government has been watching him carefully] for six months. ▪ They're keeping him at the hospital for observation [=so that doctors can watch him carefully] for another few days.
b [count] : something you notice by watching and listening
▪ Observations made using the telescope have led to new theories. ▪ Some interesting observations came from the study. ▪ scientific observations
c [count] : a written or spoken report or description of something that you have noticed or studied
▪ He recorded his observations in a notebook. 3 [noncount] : the act of doing what is required by a custom, rule, law, etc. : observance — usually + of ▪ observation of the law