Definitions

We often hear people ask to define certain words before diving into complicated topics, or people will say "by definition" as some defeater to an argument. In the former case, it seems this is done because certain words can mean different things in different contexts and it cannot always be guaranteed that everyone will have the same understanding of the word, so asking for a definition from someone is an effort in reaching consensus in parlance and making contexts clear so that people don't talk past eachother. In the latter case, the person seems to be implying that a consensus of a word has already been reached and that the definition of the word must set further grounds of the debate or discussion.

When we provide a definition in case one, we often just go by the consensus given by a trusted authority, like wikipedia, or provide context if the authority has more than one available. However, imagine that someone has discovered something new and has to come up with a definition for it, what would they need to provide so that the definition is useful to others? The following three concepts are things I've found are needed in order for a definition to be useful: Identity, Function, Causality.

Identity pertains to the discovered thing's properties and will be the primary aspect determining the formation of categories and whether the thing fits in certain categories. People will use these properties to identify the thing being defined and infer other properties, since members of the same category tend to share properties.

Function pertains to how people will expect to interact with it and the kinds of changes the thing being defined can bring about as a result of its functions.

Causality pertains to how/why the thing is the way it is now and how it can change in the future.

Example - Objectivity

I've often seen people define objectivity as "that which is independent of the mind", where things dependent on the mind are subjective. This forms a dicotomy between objectivity and subjectivity and implies that if something is subjective then it cannot be objective and vise versa. However this definition is unsatisfying, it rings more like a principle rather than a definition, a shortcut to quickly understand what people mean by objectivity.

A better definition of objectivity would be one that fulfills the three aspects, so that we can better identify what counts, how it's useful and what causal roles it plays. 

Objectivity: an arrangement of matter shaped into a precision tool that allows for the accurate represention of something else in the world [identity]. In contrast to subjectivity, the representation allows for the easy sharing of data with others and allows for the data to take part in long chains of reasoning with minimal degradation [function]. The senses are a type of crude instrument that represents the world in the mind, and thus subjectivity is a type of crude objectivity, but because our senses are inaccurate, we invented more precise measuring tools. These tools allow us to get a better understanding of the world [causality].

This definition allows for a greater degree of interpretation while staying true to the original meaning, and it doesn't doom us into disregarding something as just subjective or objective just because the definition deems the concept a dichotomy. Measurements, once performed, are independent of the mind; the senses can perform crude measurements. There's a spectrum between objectivity and subjectivity and the grading between them depends on the precision of the instrument, regardless of whether the instrument is a biological eye or a camera.