An old term for a small gap or opening in a fence or hedge — a chink through which one can just see something.
垣間（かきま）から庭の梅の枝が見えている。
Through a gap in the fence, I can see the plum branches in the garden.
垣間をのぞくと、猫が昼寝していた。
When I peered through the chink in the hedge, a cat was napping.