To wax poetic means to speak or write about something in an enthusiastic, elaborate, or excessively poetic manner. It often involves using flowery language, vivid imagery, and a heightened emotional tone to describe a subject. This phrase is typically used when someone becomes particularly passionate or expressive about a topic, sometimes to the point of exaggeration.
The term wax in this context comes from an old English usage meaning to grow or to become, while poetic refers to the style of poetry, which is known for its artistic and expressive language. So, when someone waxes poetic, they are essentially growing more poetic in their expression.
For example, someone might wax poetic about their favorite book, describing it in such a way that it feels almost magical or larger than life. This expression is often used in a positive sense, but it can also be used humorously or critically if someone is seen as being overly dramatic or verbose.