Answer:
In the poem "The Song of Wandering Aengus" by W.B. Yeats, the phrase "glimmering girl" refers to a supernatural, mystical figure that the speaker encounters in his wanderings. She is described as having "apple blossom in her hair" and as appearing to the speaker as a vision of beauty and enchantment. The phrase "glimmering" suggests a quality of radiant or shimmering light, which reinforces the idea of the girl's otherworldly beauty and allure. Overall, the "glimmering girl" represents a symbol of the speaker's yearning for a spiritual or mystical connection with the world, and his search for meaning and purpose in life.