knockings

there were strange knockings at the door last night.

she heard persistent knockings that made her uneasy.

the knockings continued until someone answered.

his knockings echoed through the empty hall.

she ignored the knockings, thinking it was just the wind.

after the knockings, a figure appeared in the shadows.

the knockings grew louder as they approached the house.

he was startled by the sudden knockings on the window.

they exchanged glances when they heard the knockings.

what do the knockings mean in this context?