| name | ubiquitous-language |
| description | Extracts DDD ubiquitous language glossary, flags ambiguities, saves to UBIQUITOUS_LANGUAGE.md. Triggers: define domain terms, build glossary, harden terminology, DDD, domain model. |
| user-invocable | true |
| effort | medium |
| argument-hint | [domain or context to extract terms from] |
| allowed-tools | Read, Write, Edit, Grep, Glob |
Ubiquitous Language
$ARGUMENTS
Extract and formalize domain terminology into a consistent glossary.
Usage
/ubiquitous-language [domain or context]
What This Command Does
- Scans conversation for domain-relevant nouns, verbs, and concepts
- Identifies ambiguities, synonyms, and overloaded terms
- Proposes canonical glossary with opinionated term choices
- Writes to
UBIQUITOUS_LANGUAGE.md
Process
- Scan conversation for domain terms
- Identify problems:
- Same word used for different concepts (ambiguity)
- Different words used for same concept (synonyms)
- Vague or overloaded terms
- Propose canonical glossary
- Write to
UBIQUITOUS_LANGUAGE.md
- Output summary inline
Output Format
# Ubiquitous Language
## {Domain Group}
| Term | Definition | Aliases to avoid |
|------|-----------|-----------------|
| **Order** | A customer's request to purchase one or more items | Purchase, transaction |
## Relationships
- An **Invoice** belongs to exactly one **Customer**
## Example dialogue
> **Dev:** "When a **Customer** places an **Order**..."
> **Domain expert:** "..."
## Flagged ambiguities
- "account" was used to mean both **Customer** and **User** — ...
Rules
- MUST be opinionated — pick the best term and list alternatives as aliases to avoid
- MUST flag every ambiguity (one word → two concepts) and every synonym (two words → one concept) with an explicit recommendation
- MUST write tight definitions (one sentence) that define what the term is, not what it does
- NEVER include generic programming concepts (array, function, endpoint, class) — this glossary is for the domain, not the toolchain
- NEVER silently overwrite an existing
UBIQUITOUS_LANGUAGE.md — read the current file first, then update incrementally preserving prior decisions
- CRITICAL: show relationships with cardinality ("an Order belongs to exactly one Customer"). Vocabulary without relationships is a word list, not a language.
- MANDATORY: include 3-5 example dialogue exchanges showing correct usage. Abstract glossaries without dialogue rarely get adopted.
Gotchas
- Domain terms often overlap with framework jargon (e.g., "Service" in DDD vs "Service" in Angular). If the framework already claims a term, prefer a domain-specific alternative to avoid collision.
- Stakeholders resist terminology change even when their current terms are ambiguous. "Account" replacing "User" triggers more discussion than expected — plan for negotiation in the example dialogue section.
- Glossaries rot when features ship without updating them. A
UBIQUITOUS_LANGUAGE.md last updated 6 months ago is a snapshot, not a source of truth. Flag staleness in the header and re-run this skill periodically.
- Relationships between terms are easy to hand-wave with "related to". Pin down the cardinality (
0..1, 1..*, 1..1) — vague relationships produce schema ambiguity later.
- The opinionated canonical choice may contradict marketing or legal language. Note conflicts explicitly rather than hiding them; the domain model and the marketing site can legitimately diverge.
When NOT to Use
- For writing a PRD (full requirements) — use
/write-a-prd
- For generating user-facing documentation — use
/docs
- For implementation planning — use
/plan or /prd-to-plan
- For enforcing language in commit messages or code reviews — use
/brand-voice (distinct concern: writing style, not domain terms)
- When the project is a single-developer throwaway — glossary overhead is not justified
