In research, categories of recurring facts, themes, comments, and the like selected from fieldnotes for attention because they are likely to help explain a situation of interest. Once established, new fieldnotes are coded into these categories.
The process of substituting a symbol (code), usually a numeric or alphanumeric string of characters, for a term, such as a diagnosis or procedure. Of course, every term coded can be decoded, i.e., the code can be looked up and one can find precisely the term which it represents.
In billing for medical services, the grouping of medical diagnoses within an established category, usually with standard symbols such as those in the International Classification of Diseases.