The flickering light on the porch threw some dactyls at him

Context is all. Harry had sneaked out onto the porch for a cigarette but Aunt Aurelia appeared almost as soon as he lit up, looming silently as the first emissions from the first delicious drag swirled round his head. Caught thus in flagrante, he sought refuge in wit. "Ill met by porchlight, proud Aurelia", he declaimed, with the hopeless braggadocio of a cornered raccoon.

But, on the other hand, Ernestine has never been the same since Tom went missing. She refuses to have him declared dead and insists on leaving the porch light on so he can find his way home.

Porch-light, however, is an abomination.

Ann: you do realize that you now have to write the rest of that story. Not knowing what happened to poor Tom is going to keep me up at night.

Heh-heh-heh... gotcher!

But I believe we are of a mind regarding the exterior illumination.

Thanks, everyone. I have been working on a weird little poem and haven't been sure as to whether I needed a noun or an adjective, so this has all been very helpful.

Also, I will always take great pride in having inspired Ann's future best-selling novel. Moreover, I will never look at the nocturnal burglars of our garbage cans by our fence in the same way.

I would tend to use porch-light, although porch light doesn't offend me. But porchlight would certainly be wrong since, like "sunlight", it would mean, not the light installed on the porch, but the light emanating from the porch.

Actually, with the last revision, that's exactly what I want.