I was tagging post #540314 and wanted a tag for when a woman's hair is splayed out on a bed or other surface she's laying back on.

Do we have a tag for this already?

No, we don't, but it's basically every image of lying on_back long_hair.
Your example is pretty bad, try
post #1057426, post #1067042, post #516423

Eh, that's just the image that prompted it in my mind. But it is a good image for showing that the concept is not limited to long hair or very long hair.

Dangit, looks like I've managed to give myself another huge tagging project. What's a good name for the tag?

So far I've got:

• hair splayed out
• hair spread out
• hair laid out
• hair fanned out

From what we've got I think hair spread out is probably the best, and I can definitely get behind it as a good taggable concept. There is probably also a pretty large overlap with messy hair that should probably be considered when tagging this, depending on how even / uneven the hair is spread.

Did we ever come to a decision on this? I notice none of these seem to be in active use.

hair_spread_out looks fine to me