noun
circumstance
SUR-kuhm-stans/ˈsɜːrkəmstæns/
A fact or condition that affects a situation.
The flooded path is a circumstance that changes their route.

Etymology
The image is of things “standing around” an event: its surrounding conditions. A circumstance is thus a fact that affects a situation without being its essential core.
In context
in a normal circumstance you don't want anything in your subepithelial space in fact you want your you want that space to be gone