What does simile mean?

Simile means a nonliteral (figurative) comparison made between unlike things using the words “as,” “like,” or “than.” For example, “She moved as fast as lightning.”

It differs from metaphor, which makes the same kind of comparison using a form of the verb “be” (e.g., “She was lightning”).

Similes are used to express a quality in a vivid way. They are encountered frequently in literature and song lyrics (e.g., “My love, she speaks like silence”), but they also appear in everyday conversation, in many common expressions (e.g., “light as a feather”).