Vocabulary tools split into four kinds: glossary, dictionary, taxonomy, style guide

"Cash flow is the flow of cash through a business." That sentence has the shape of a definition and does none of the work. It restates the term using the term. A reader who did not know what cash flow was still does not.

This page cannot honestly rank reference works. It can give you the test that separates a definition from a restatement.

It can also define the words that describe the references themselves, since those are mixed up constantly. Picking the wrong kind of reference is the more common mistake.

What to take away

The test: class, then difference

A working definition names the broader class a thing belongs to, then states

Applied to the failed example, cash flow belongs to the class movements of money in and out of an entity over a period.

It counts money actually received and paid, when it moves, and ignores amounts earned or incurred but not yet settled. That separates it from profit, which readers confused it with.

Three failures are easy to spot once you look for the two moves.

Circularity. The definition uses the term, or an obvious cousin of it. "Working capital is the capital used in working operations."

Class with no difference. "A budget is a financial plan." True, and so is a forecast, a cash-flow projection, and a business case. The sentence has named the class and stopped.

Examples instead of a definition. "Fixed costs are things like rent and insurance." A list of instances is useful after a definition. On its own it leaves the reader unable to classify anything not on the list, and it hides the fact that fixed cost describes how a total behaves rather than what kind of thing it is. The two axes that sort costs are separated in the business vocabulary guide.

The kinds of reference, defined

These are not interchangeable, and the differences matter when you are choosing

Glossary. A list of terms with short definitions, scoped to a particular document, field, or audience. A glossary is bounded on purpose: it explains the terms that appear in the thing it accompanies.

Named examples include Collibra Glossary, Atlan Glossary, and Alation Business Glossary. A typical small-business glossary holds 20 to 60 terms.

Lexicon. The whole vocabulary of a field, or a work attempting to record it. Broader than a glossary and not tied to a single document.

Data dictionary. Definitions of the fields in a system or dataset: what each field holds, its type, its permitted values, where the value comes from, and who owns it. A data dictionary defines columns, not concepts. Asking one to explain what a customer is will disappoint you; asking it what the customer_id field contains is exactly its job.

General dictionaries such as Merriam-Webster and the Oxford English Dictionary define words. Named data dictionary tools include Dataedo, ER/Studio Data Architect, and Oracle SQL Developer Data Modeler. A typical data dictionary documents 50 to 500 fields per system.

Controlled vocabulary. A fixed list of permitted terms, where using a term outside the list is an error. Its purpose is consistency, not explanation.

Taxonomy. A hierarchy of categories, where each item sits under a parent. It tells you what something is a kind of.

Named taxonomy tools include PoolParty, Synaptica, and Smartlogic. A typical business taxonomy has 3 to 7 levels.

Ontology. Terms plus the defined relationships between them, not just "invoice is a kind of document" but "an invoice references an order and triggers a payment". An ontology can answer questions a taxonomy cannot.

Style guide. Rules about how to write, including which term to prefer. It governs usage; it does not define concepts.

Named style guides include The Chicago Manual of Style, The Associated Press Stylebook, and the Microsoft Writing Style Guide. A typical corporate style guide runs 20 to 100 pages.

The practical consequence: a glossary will not fix two teams reporting different numbers for the same word. That is usually a denominator problem, and the metric words guide explains why.

You need field-level definitions and source rules for that data dictionary problem, while a glossary is exactly right if new joiners cannot read the internal shorthand.

The kinds of definition

Nominal definition. States what a word means, in terms of other words. Most dictionary entries are nominal.

Operational definition. States the procedure by which you decide whether the term applies, in a way two people can follow and reach the same answer. This is the property the assessment guide calls consistency, and it is what makes a definition usable by more than one person. "An active customer is one who placed at least one order in the current period" is operational. "An active customer is one who is engaged with us" is not.

Stipulative definition. Announces a meaning for use within a specific document, whether or not that matches ordinary usage. This is what a contract's definitions clause does.

Defined term. A term a document has given a stipulated meaning, usually signalled by capitalization. Inside that document, the stipulated meaning wins over the ordinary one, however strange it looks. A clause defining Business Day so that it excludes a particular weekday is not a mistake; it is the definition that governs.

Term of art. A word with a settled technical meaning inside a field, which differs from its everyday meaning. Consideration, material, security, discharge, provision: each has an ordinary sense and a technical one, and the technical one is what applies in a contract, a filing, or a regulatory submission. Where a term has a specific accounting, tax, or legal meaning, that meaning is the one that binds in a document, regardless of how the term is used in a meeting.

What to check before trusting any reference

Two boundaries worth having in front of you

Term against concept. A term is a label; a concept is the thing labeled. Two teams can use one term for two concepts, which reads as agreement and behaves as disagreement. They can also use two terms for one concept, which reads as disagreement and is merely vocabulary.

Definition against description. A definition draws a boundary: it lets you say whether a new case is in or out. A description tells you what typical cases look like. Descriptions are useful and are not substitutes. "Recurring revenue tends to be predictable" is a description. A definition would say what makes revenue recurring rather than repeated.

For official wording of investment and finance terms, a public glossary from a securities regulator gives the definition an authority actually uses. Copy that version when the term appears in anything formal.

For the wider set of terms this site covers, start at the twelve worked examples. They show the same words used loosely in a meeting and precisely in a document.

Common questions

Should a small business write a glossary at all?

Only for the terms two people have already disagreed about. A glossary written in advance for terms nobody has argued over is a document nobody will open. Start from the argument.

Where should the definitions live?

Wherever the argument happens. A definition in a policy document nobody reads does not settle anything; the same definition in the report where the figure appears does.

Who owns a definition once it exists?

One named person, who is also the person to ask when a new case does not fit. Definitions without an owner drift, because each team resolves edge cases its own way and nobody notices until the numbers differ.

What if an authority defines the term differently from us?

Then use the authority's wording anywhere the term will appear in something formal, and say plainly in your internal document that you are using a narrower sense. Two definitions, both labeled, cause far less trouble than one undeclared local meaning.