Appositive Phrase
Punctuation depends on whether the appositive is necessary to identify the referent in context. The phrase can follow or precede the noun it explains, and commas signal supplemental rather than identifying information.
An appositive phrase is a noun phrase placed beside another noun phrase to identify, rename, or explain it. Nonessential appositives are usually set off with commas, while essential appositives normally are not.
Key details
Important caveats
Boundary
If the appositive is needed to identify which person or thing is meant, surrounding commas can wrongly imply the information is optional.
Further guidance
Diagnostic
Find the two noun phrases and ask whether one renames or identifies the other.
Punctuation
If removing the appositive leaves the intended referent already clearly identified, treat the appositive as supplemental and normally set it off.
Worked Example
“Mina, the project editor, approved the draft” treats “the project editor” as supplemental; “the poet Sappho” uses the name restrictively and normally takes no comma.
Sources and evidence
Sources are shown with the role they play in this guide. Historical or style-sensitive claims are kept within the evidence boundary described above.
- Appositives (opens in a new tab)Purdue Online Writing Lab · Defines appositives/appositive phrases and distinguishes essential from nonessential appositives for comma punctuation.
- Extended Rules for Commas — Purdue OWL (opens in a new tab)Purdue University · Direct punctuation guidance for commas in geographical names and addresses.