Coordinate nouns and adjectives that are not joined by coordinating connectives are punctuated as follows:
Coordinate adjectives are those that each independently modify the same noun. They are separated by commas (but the last adjective can’t be followed by a comma):
We’re looking for a strong, resourceful frog.
Fang is all set for some yummy, nutritious Cobra Chow.
A smooth, agile, good-humored elephant would make a great addition to the ballet corps.
An easy test for whether adjectives are coordinate would be to try to join them with and. If they make sense that way, they are coordinate (but not punctuated):
We’re looking for a strong and resourceful frog.
Fang is all set for some yummy and nutritious Cobra Chow.
A smooth and agile and good-humored elephant would make a great addition to the ballet corps.
Another reliable test is to try to change the order of the adjectives. We could say a resourceful, strong, frog or an agile, good-humored, smooth elephant..
Only coordinate adjectives can be separated by commas. Many adjective phrases do not consist entirely of coordinate adjectives or do not contain any at all:
I’d like to take a moderately overpriced winter weekend vacation.
No commas are possible here since there are no coordinate modifiers. Moderately modifies overpriced; overpriced modifies winter weekend vacation; winter modifies weekend vacation; and weekend modifies vacation. Nor could we place and between the adjectives:
ERROR: I’d like a moderately and overpriced and winter and weekend vacation.
He’s an expert on nineteenth-century rural Quebec gas-station architecture.
There are no coordinate modifiers here, so we couldn’t change the word-order or insert and between the modifiers. Gas-station modifies architecture; Quebec modifies gas-station architecture; rural modifies Quebec gas-station architecture, and nineteenth-century modifies rural Quebec gas-station architecture.
Items in Series
A series is a listing of three or more coordinate elements. The elements are ordinarily separated by commas, and a coordinating connective usually comes between the next-to-Iast and last item. I’ve italicized the coordinate elements in the following examples:
Ms. Beebs loves commas, semicolons, and colons.
He huffed, puffed, blew the house down, and built a condo on the site.
The mouse ran up, down, and around the clock.
The last comma in a series, the one before the coordinating connective, is optional, and most writers leave it out.
If the items in a series include commas, the items need to be separated with semicolons:
I’ve been reading about that cantankerous, impatient Donald; that decisive, delightful Daisy; and those wild nephews, Huey, Dewey, and Louie.