Term

A Term is a glossary entry that defines vocabulary used within a domain or context. Since Domain-Driven Design requires bounded contexts to have precise, unambiguous terminology, RIDDL provides the Term definition to capture word meanings that aren't modeled as types or entities.

Purpose

Terms help you:

• Establish ubiquitous language: Define the shared vocabulary of your domain
• Avoid ambiguity: Clarify words that might mean different things to different people
• Document domain knowledge: Capture business concepts that don't need formal modeling
• Generate glossaries: Tools can extract terms into documentation

Syntax

Terms appear in with { } metadata blocks, not inside a definition's body. The syntax is term identifier is doc_block:

domain ECommerce is {
  ???
} with {
  term Customer is {
    |A person or organization that has purchased products or
    |services from us, or has expressed interest in doing so.
    |Distinguished from a "Lead" (who hasn't yet engaged) and
    |a "User" (who accesses our systems but may not be the
    |purchaser).
  }
}

Example: E-Commerce Domain

domain ECommerce is {
  context Catalog is {
    // ... body definitions (entities, types, etc.) ...
    ???
  } with {
    term Listing is {
      |A product's presence in the catalog, including its
      |description, images, pricing, and availability. One
      |product may have multiple listings in different
      |categories.
    }
  }

  context Orders is {
    ???
  } with {
    term Fulfillment is {
      |The complete process of receiving, processing, and
      |delivering an order to the customer. Includes picking,
      |packing, shipping, and delivery confirmation.
    }
    term Backorder is {
      |An order for a product that is temporarily out of stock.
      |The order is accepted but fulfillment is delayed until
      |inventory is replenished.
    }
  }
} with {
  term SKU is {
    |Stock Keeping Unit. A unique identifier for a specific
    |product variant, including size, color, and other
    |attributes. Example: "SHIRT-BLU-L" for a large blue shirt.
  }
  term CartAbandonment is {
    |When a customer adds items to their shopping cart but leaves
    |the site without completing the purchase. A key metric for
    |conversion optimization.
  }
}

Terms vs. Types

Concept	When to Use
Term	Word definitions, business jargon, conceptual explanations
Type	Data structures that appear in messages, states, or APIs

If you need to pass it in a message or store it in state, use a Type. If you're defining what a word means, use a Term.

context Orders is {
  // Use a Type when you need the data structure
  type Money is { amount: Decimal, currency: CurrencyCode }
  ???
} with {
  // Use a Term when you're defining the concept
  term Revenue is {
    |The total income generated from sales before deducting
    |costs and expenses. Distinct from "profit" which is
    |revenue minus costs.
  }
}

Best Practices

1. Define early: Add terms as soon as domain vocabulary emerges
2. Be specific: Include examples and distinguish from similar concepts
3. Keep current: Update terms as understanding evolves
4. Cross-reference: Mention related terms and types in definitions
5. Involve domain experts: Terms should reflect how the business talks

Occurs In

Metadata blocks (with { }) on any definition.

Contains

Nothing (leaf definition with description only)