adjectives: comma use
Comma use with adjectives that describe the same noun or pronoun.
Use commas between coordinate adjectives when no conjunction joins them: We rented a quiet, spacious apartment. Coordinate adjectives describe the noun independently; here, quiet and spacious each describe apartment.
If you can insert and or reverse the order without changing the meaning, the adjectives are coordinate and take a comma: a quiet and spacious apartment; a spacious, quiet apartment.
Cumulative adjectives take no comma. They combine in sequence, with an earlier adjective modifying the group that follows: She bought a small round mirror. Here, small modifies round mirror.
A sequence may contain both kinds of adjectives: They faced a long, expensive legal dispute. Long and expensive independently describe legal dispute, so a comma separates them. Legal identifies the kind of dispute and stays with the noun, with no comma before it.
The last adjective joins its noun directly, with no comma: She submitted a clear, detailed report. When and joins two adjectives, they take no comma: We need a reliable and affordable service.
See also comma; commas in lists.
Examples
UseThe mechanic gave a patient, thorough explanation. (Patient and thorough are coordinate adjectives, so a comma separates them.)
UseWe replaced the old wooden gate. (Old and wooden are cumulative adjectives: old modifies wooden gate, so no comma is needed.)
UseIt became a bitter, protracted political debate. (Bitter and protracted are coordinate adjectives, so a comma separates them. Political is cumulative: it identifies the kind of debate and stays with the noun, so no comma comes before it.)
AvoidThey offered a practical, economical, solution. (The comma after economical wrongly separates the last adjective from its noun.)