Bookworm by William Henry Clapp depicts a nude figure lying on their back draped across what appears to be a bed or a cot. The person's left arm is bent with their hand gently resting across their face, which is turned away from the viewer. Their right arm is extended outwards, relaxed, with the hand slightly curled. The figure's pose conveys a sense of repose or perhaps languid study or reading.

In the foreground, there is an open book, suggesting that the figure might have been reading before resting. The cover of the book is visible, but the text or images cannot be made out clearly. The book and the figure are the focal points of the composition, with the figure's skin tones rendered in soft, warm hues that contrast with the white of the sheets they lie upon.

The background is less defined, composed of impressionistic brushstrokes in green, yellow, and purple, which suggest a light-dappled space, possibly outdoors due to the hints of green implying foliage. The overall effect is one of quiet leisure and intimacy, with the viewer given a snapshot into a private moment of repose.

The painting style is impressionistic, with visible brushstrokes and a vibrant play of light and color that provide a sense of texture and movement. It captures an ephemeral quality of light, which is characteristic of the Impressionist movement, emphasizing the sensory effect of the scene rather than the fine detail.