Slacks are a type of men's trousers characterized by a loose or relaxed fit, typically made from lightweight fabrics such as wool, wool blends, cotton, linen, or polyester blends. They are designed to be comfortable and stylish, often featuring a straight or slightly tapered leg. Slacks are generally dressier than casual pants like jeans or chinos but less formal than suit pants, making them versatile for both casual and semi-formal occasions

. The term "slacks" originally comes from an old Saxon word meaning "loose," reflecting their comfortable, non-tight fit. While slacks and dress pants are often used interchangeably, slacks tend to emphasize comfort with a looser cut, whereas dress pants are more tailored and structured for formal or professional settings. Dress pants usually have a more fitted silhouette, higher waist rise, and may include design details like pleats or cuffs, whereas slacks have a more relaxed construction and simpler design

. In summary:

• Slacks : Loose-fitting, comfortable trousers made from lightweight fabrics, suitable for casual to semi-formal wear.
• Dress pants : More tailored, structured trousers designed for formal or professional occasions.
• Slacks vs. Chinos : Chinos are casual cotton pants with a more casual cut and some elasticity, distinct from slacks

Thus, slacks are essentially dress pants with a relaxed fit and focus on comfort and versatility.