隙 - crevice, fissure, discord

gap; opening; room; space

gap; opening; aperture; crevice; crack; chink; space

gap

caulking; calking

before one could; in no time at all; without a gap

gap; opening; space

peeping

spare moment; free time; interval; break

to watch for an unguarded moment

one must constantly be on one's guard with ...; one cannot be too careful of ...

niche market

time flies; like watching a white horse run by through a gap in the wall (Zhuangzi)