When the speaker in william wordsworth i wandered lonely as a cloud describes a host of daffodils tossing their heads in sprightly dance he is using

Personification to bring the flowers he saw to life.

Explanation:

Personification is the attribution of humanistic qualities to non human ideas or abstract things. This allows the non living things to have living attributes, making them seem as if they are also living and have their own qualities and concepts.

William Wordsworth uses this figurative language in his poem "I Wondered Lonely As A Cloud" and gave the flowers a humanistic quality. He addressed he daffodils as if they are human, "dancing in the breeze", "Tossing their heads in sprightly dance". Not only that, he also personifies his heart as "danc(ing) with the daffodils."