Final answer:
The narrator frequently uses the word 'creeping' to describe the movement of the woman in the wallpaper, signifying a stealthy and unsettling movement.
Step-by-step explanation:
The word that the narrator frequently uses to describe the movement of the woman in the wallpaper is creeping. This term is used multiple times throughout the text to convey a particular kind of secretive or slow movement, often associated with a sense of unease or stealth. The references to the woman creeping by daylight, hiding under vines when seen, and finally the narrator herself feeling compelled to creep around, create a pervasive theme of this eerie movement within the story.