aperture

/ˈæpərˌtʃər/
/ˈæpərˌtʃʊr/

noun

An opening, hole, or gap.

the bell ropes passed through apertures in the ceiling

opening,hole,gap,space,slit,slot,vent,passage,crevice,chink,crack,fissure,perforation,breach,eye,interstice