How do the meaning is words such as "yellow" and "creeping" change as the story goes on

In the story, wallpaper, a usually feminine, floral decoration on the interior of walls, is a symbol of female imprisonment within the domestic sphere. Over the course of the story, the wallpaper becomes a text of sorts through which the narrator exercises her literary imagination and identifies with a feminist double figure.

When John curbs her creativity and writing, the narrator takes it upon herself to make some sense of the wallpaper. She reverses her initial feeling of being watched by the wallpaper and starts actively studying and decoding its meaning. She untangles its chaotic pattern and locates the figure of a woman struggling to break free from the bars in the pattern. Over time, as her insanity deepens, she identifies completely with this woman and believes that she, too, is trapped within the wallpaper. When she tears down the wallpaper over her last couple of nights, she believes that she has finally broken out of the wallpaper within which John has imprisoned her. The wallpaper's yellow color has many possible associations - with jaundiced sickness, with discriminated-against minorities of the time (especially the Chinese), and with the rigid oppression of masculine sunlight. By tearing it down, the narrator emerges from the wallpaper and asserts her own identity, albeit a somewhat confused, insane one. Though she must crawl around the room, as the woman in the wallpaper crawls around, this "creeping" is the first stage in a feminist uprising.

Sunlight vs. Moonlight

Although the yellow color of the wallpaper has associations with illness, its most developed motif is the conflict between sunlight and moonlight. In Gilman's story, sunlight is associated with John's ordered, dominating schedule and the rational sphere of men. John prescribes something for the narrator for every waking hour while he goes about his daily rounds, forcing her to take on the same order and control that defines his life.

At night, however, the balance shifts. Men's day jobs in the public sphere are irrelevant, and women can achieve a more equal level with their husbands. While he is asleep, John is unable to monitor the narrator’s behavior, and she is not in a perpetual state of inferiority or being constantly controlled. More importantly, the narrator’s flexible subconscious roams free at night, as in during dreams. It is always by moonlight, a traditional symbol of femininity and the Goddess Artemis, that the narrator understands more about the figure trapped within the wallpaper. In sunlight, the woman stays still, afraid of being caught, and, once she creeps about outside, she does so boldly only at night. Moreover, the narrator cannot see the figure under the oppressive glare of sunlight in her room and is overwhelmed by the pattern of the wallpaper. By the cool, feminine light of the moon, the narrator is able to grasp the woman’s plight and ultimately recognize in it a reflection of her own imprisonment.

The choice of the word "creep," where one might instead choose the word "crawl," connotes a feeling of creepiness, which is a good word to describe the whole story. As a reader, one is creeped out by the narrator's growing insanity and obsession with the wallpaper.

Creepiness has to do with ambiguity, which the story is also full of; the narrator shows, through her language, very mixed feelings towards the paper, as well as to her husband.

Sunlight vs. Moonlight

Although the yellow color of the wallpaper has associations with illness, its most developed motif is the conflict between sunlight and moonlight. In Gilman's story, sunlight is associated with John's ordered, dominating schedule and the rational sphere of men. John prescribes something for the narrator for every waking hour while he goes about his daily rounds, forcing her to take on the same order and control that defines his life.

At night, however, the balance shifts. Men's day jobs in the public sphere are irrelevant, and women can achieve a more equal level with their husbands. While he is asleep, John is unable to monitor the narrator’s behavior, and she is not in a perpetual state of inferiority or being constantly controlled. More importantly, the narrator’s flexible subconscious roams free at night, as in during dreams. It is always by moonlight, a traditional symbol of femininity and the Goddess Artemis, that the narrator understands more about the figure trapped within the wallpaper. In sunlight, the woman stays still, afraid of being caught, and, once she creeps about outside, she does so boldly only at night. Moreover, the narrator cannot see the figure under the oppressive glare of sunlight in her room and is overwhelmed by the pattern of the wallpaper. By the cool, feminine light of the moon, the narrator is able to grasp the woman’s plight and ultimately recognize in it a reflection of her own imprisonment.

(Note: This is from my own perspective of the novel's content and theme. Please do not think I had copied Jill's answer because I did not. Thank you).