Reply #4: Both [View All]

[MountainLaurel]

When it's used as a unit modifier, it's one word. In other usage as a full noun, it's two. For example:

The healthcare system in the United States bites the big banana.

The unfortunate family had to sell their prized heirlooms in order to pay for health care.

(Edited because I'm a doofus who cannot string the proper thoughts after 10 pm. Besides, I am no longer an editor, so I really shouldn't care. Hooray for career changes! :party:)