Definitions, like questions and metaphors, are instruments for thinking. Their authority rests entirely on their usefulness, not their correctness. We use definitions in order to delineate problems we wish to investigate, or to further interests we wish to promote. In other words, we invent definitions and discard them as suits our purposes. And yet, one gets the impression that... God has provided us with definitions from which we depart at the risk of losing our immortal souls. This is the belief that I have elsewhere called "definition tyranny," which may be defined... as the process of accepting without criticism someone else's definition of a word or a problem or a situation. I can think of no better method of freeing students from this obstruction of the mind than to provide them with alternative definitions of every concept and term with which they must deal in a subject. Whether it be "molecule," "fact," "law," "art," "wealth," "gene," or whatever, it is essential that students understand that definitions are hypotheses, and that embedded in them is a particular philosophical, sociological, or epistemological point of view.

Rules for Definitions. I. Not to undertake to define any of the things so well known of themselves that the clearer terms cannot be had to explain them. II. Not to leave any terms that are at all obscure or ambiguous without definition. III. Not to employ in the definition of terms any words but such as are perfectly known or already explained.

Odd that we think definitions are definitive.

To define something is to subordinate it to a tangle of intellectual relationships. And when you do that you destroy real understanding.

an obsession with self-definition can become a trap if that is all we think about, all we debate. If liberation terminology becomes an end in itself and our only end, it ceases to be a tool of liberation. Terms can be useful, even vital tools, but the house of La Raza that is waiting to be built needs many kinds. (“A Word About the Great Terminology Question ”)

It is hard to define something one knows little about

There surely is something to these terms, but too often they’re the result of minds intent on discovering meaning where there is only probability.

Political debate can barely occur in an atmosphere in which people assume words and terms to have distinctly different meanings. They slide, slip and decay. But in the world we are in – where anybody might edit a Wikipedia definition, and where plenty of people are learning on the hoof about complex and disputed ideas – we need to try to agree on what words mean rather than define them for ourselves.

Definitions belong to the definers, not the defined.

Whenever we proceed from the known into the unknown we may hope to understand, but we may have to learn at the same time a new meaning of the word 'understanding.

"Any concepts or words which have been formed in the past through the interplay between the world and ourselves are not really sharply defined with respect to their meaning: that is to say, we do not know exactly how far they will help us in finding our way in the world. We often know that they can be applied to a wide range of inner or outer experience, but we practically never know precisely the limits of their applicability. This is true even of the simplest and most general concepts like "existence" and "space and time". Therefore, it will never be possible by pure reason to arrive at some absolute truth.
The concepts may, however, be sharply defined with regard to their connections. This is actually the fact when the concepts become part of a system of axioms and definitions which can be expressed consistently by a mathematical scheme. Such a group of connected concepts may be applicable to a wide field of experience and will help us to find our way in this field. But the limits of the applicability will in general not be known, at least not completely."

For to define is to isolate, to separate some complex of forms from the stream of life and say, “This is I.” When man can name and define himself, he feels that he has an identity. Thus he begins to feel, like the word, separate and static, as over against the real, fluid world of nature.

We can't define anything precisely. If we attempt to, we get into the paralysis of thought that comes to philosophers... one saying to the other: you don't know what you are talking about! The second one says: what do you mean by talking? What do you mean by you? What do you mean by know?

Every one has experienced how learning an appropriate name for what was dim and vague cleared up and crystallized the whole matter. Some meaning seems distinct almost within reach, but is elusive; it refuses to condense into definite form; the attaching of a word somehow (just how, it is almost impossible to say) puts limits around the meaning, draws it out from the void, makes it stand out as an entity on its own account.