Flâneur means “stroller,” “lounger,” “saunterer,” or “loafer.” Flânerie refers to the act of strolling (Wikipedia). Flâneur is the masculine term, the feminine version being a flâneuse. It is a word borrowed from the French noun.
Back in 19th century France, a flâneur was a literary type person, a jaunter often seen strolling the streets of Paris. However, the nonchalant strolling in Paris didn’t inspire romantic sentiments before that; in the 16th and 17th centuries, the term usually had the connotation of someone wasting time.