---
id: dwd_6prph2yy
type: term
slug: data-dictionary
title: "Data dictionary"
summary: "A column-by-column reference for one system: each field's type, allowed values and local definition."
status: draft
classification: public
authors:
  - name: Shan Umasankar
    url: https://dealwithdata.com
    role: author
assisted_by: [Claude]
scales: [personal, business, enterprise]
synonyms: ["source data dictionary"]
broader: [dwd_gubdecks]
related: [dwd_wg5zzqg2]
created: 2026-10-07
updated: 2026-10-07
version: 1
---
A data dictionary documents a single source system from its own point of view: every table and field, its type, its allowed values, and what it means *in that system*.

**Example**

| Column | Type | Definition | Allowed values |
|---|---|---|---|
| `OUTSTANDING_BAL_AMT` | DECIMAL(18,2) | Unpaid principal, USD | ≥ 0 |
| `LOAN_STAT_CD` | CHAR(2) | Loan status | `AC` active, `CL` closed, `CO` charged off |

**Not to be confused with** a [[business-glossary]], which defines terms for the whole enterprise. Linking dictionary entries to glossary terms is the business-to-technical mapping.