I'm working on my story for NaNoWriMo (naturally) and I've just had one of my characters pass through a hole. It closes behind him, but I want to evoke the image of an aperture closing. As in, multiple pieces sliding together, precisely like the aperture of a camera. The first word that came to mind was "sphinctered", but that doesn't seem to be a "real" word. Is there a precise word that describes the way a camera-like aperture closes?
You might say it irised shut, using verb iris that means “(of an aperture, lens or door) To open or close in the manner of an iris” [en.wiktionary)] in past tense.
Also consider spiraled shut (which I think is a more accurate description of the curved pieces of a camera iris closing) and winked shut or blinked shut, which are less accurate for a camera iris, but perhaps may evoke the proper image for your context.
The iris of an eye does not close in the same way as that of a camera; as noted in wikipedia's Iris (anatomy) article,
The stroma connects to a sphincter muscle (sphincter pupillae), which contracts the pupil in a circular motion, and a set of dilator muscles (dilator pupillae) which pull the iris radially to enlarge the pupil, pulling it in folds.
The phrase "the door dilated" is an old SF trope, attributed to Heinlein as an example of casual world-building.
Surely "closed", from the context we get the means by which something closes.
"The X closed behind him" - consider X being "sliding door" or "garage door", you need not say, but may say "slid closed" or "came down from the ceiling".
"the aperture closed behind him" is quite boring, but you can get sound and visual information across without finding a specific word for an aperture closing, words like "contract" if it is more "organic" or the rotating of blades if it is more like a camera.
A rule I have - I stress this is entirely rooted in experience - is that operations will preserve the topology of the thing being operated on unless stated otherwise.
Saying the iris closed does not mean you suddenly have a disk that isn't punctured, to close your eyes does not mean they seal shut.