In fashion terminology, what is the general purpose of a 'trench coat'?

The trench coat is specifically designed to ensure warmth and provide weather resistance for outdoor wear. Originating from military uniforms, its structure typically includes a waterproof fabric, long sleeves, and a cinched waist that help to protect the wearer from inclement weather conditions. The double-breasted front and wide lapels are also functional as they provide additional coverage from rain and wind, making the trench coat a practical choice for various outdoor activities.

While evening wear, casual outdoor protection, and formal business attire can all have their own specified garments, the primary purpose of the trench coat aligns most closely with providing warmth and weather resistance, establishing it as an essential outer layer in fluctuating climate conditions. Its versatility also allows it to be adapted into various fashion contexts, but its core intent remains rooted in functional outdoor wear.