I expect this to become a series, so I’m numbering this post. If I’m wrong, well … I’ll come back later, in a year or two, and edit the title.
Aaaaanyway, let’s get to it.
This is about commas and adjectives. When you have a string of adjectives before a noun, how do you know if you need commas between them? (In grammar-speak, these are called coordinate or coordinating modifiers. No one remembers that, though, except for grammar geeks. Hence my choice to use plain language.)
Can you put the word “and” where a comma is without wrecking the sense (syntax) of the sentence? If you can, then use a comma. If you can’t, don’t use one.
That might not work 100% of the time, but it’ll work often enough that you’ll be safe using it as a guideline. (For the rare occasion it won’t work, your editor will catch it. You have an editor. Surely.)
Here’s an example: Hundreds of dying, beached, bottle-nosed dolphins covered the sand.
If I put “and” where those commas are, the sense gets a little weird. “Dying and beached and bottle-nosed dolphins”–what? Some are dying, some are beached, and some are bottle-nosed? We know that doesn’t sound right, but a reader could make that error. (Remember, editors read stupid.) The sense of the sentence as intended is “bottle-nosed dolphins that are dying and beached.” AHA! The “and” between “dying” and “beached” means we can put a comma there.
Dying, beached bottle-nosed dolphins.
Still don’t quite grasp it? Try this, then. Change the order of the adjectives. Can you say “bottle-nosed, dying, beached dolphins?” Well, sure, you can–but does that sound right to your ear? Probably not. Bottle-nosed dolphins. Those go together as a unit. (Same as “blue whale” or “great white shark.” Would you say “white great shark?” Nah.) However, you can say “beached, dying bottle-nosed dolphins.” The modifiers you can swap around are the ones you can put “and” between, so they’re also the ones you should separate with a comma.
Beached, dying bottle-nosed dolphins.